June 23 - 28 2013 Frauenchiemsee Germany
Mit Unterstützung durch Deutsche Forschungsgemeinschaft und STAIB INSTRUMENTS GmbH
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15th European Symposium on Gas Electron Diffraction Frauenchiemsee, Germany
June 23rd – 28th 2013
PROGRAMME
Sunday June 23
Until 18:00 Arrival / Registration
18:00 Come together / Buffet
Monday June 24 9:00 Norbert Mitzel Bielefeld, GE Opening
Molecular Movies and Clusters Chair: Norbert Mitzel
9:15 Dwayne Miller Hamburg, GE/
Toronto, CA
Making the molecular movie: The chemists’ gedanken-experiment enters the lab frame
10:00 Detlef Schooss Karlsruhe, GE Determination of metal cluster structures by Trapped Ion Electron Diffraction
10:30 Coffee break
Gas Phase Structure
Chair: David Rankin
11:00 Igor Shishkov Moscow, RU The structure of methoxyfurane and noradrenaline as studied by gas electron diffraction and quantum-chemical
calculations
11:30 Georgiy Girichev Ivanovo, RU Combined gas-phase electron diffraction and mass spectrometry: achievements and problems
12:00 End of session
12:15 Lunch
Ultrafast Processes
Chair: Dwayne Miller
13:45 Martin Centurion Lincoln, US Ultrafast electron diffraction from aligned molecules
14:30 Peter Weber Providence, US Electron and X-ray probes of molecular structure on ultrafast time scales
15:00 Dongfang Zhang
Hamburg, GE A femtosecond electron diffraction study: electronically-driven ablation via highly localized electronic states
15:30 Coffee break
Theory and Modeling
Chair: Dines Christen
16:00 Vladimir Tsirelson Moscow, RU Bonding descriptors based on electron density: how does it look now?
16:30 Carole Morrison Edinburgh, UK Exciting ”stuff”: modeling photochemical reactions in the condensed phase. Applications in time-resolved diffraction.
17:00 Michal Kochman Edinburgh, UK The mechanism of solid-state photo-isomerisation reaction
17:30 End of session
18:00 Dinner Scientific Discussions
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Tuesday June 25 Structure in Silicon Chemistry
Chair: Raphael Berger
9:00 David Scheschkewitz Saarbrücken, GE Siliconoids: stable unsaturated molecular silicon clusters
9:45 Ingvar Arnason Reykjavik, IC Properties of monohalogenated silacyclohexanes (CH2)5SiHX; X = F, Cl, Br, I
10:10 Sergey Shlykov Ivanovo, RU Silacyclohexane derivatives
10:35 Coffee break
Structural Features of Selected Compound Classes Chair: Derek Wann
11:00 Attila Kovács Karlsruhe, GE Bond length contraction in actinide compounds
11:25 Peter Pogány Karlsruhe, GE Structural properties of actinide di- and tetracarbides
11:50 Boris Lokshin, Mari-am Ezernitskaya
Moscow, RU Spectroscopic and photochemical studies of substituted cymantrenes
12:20 End of Session
12:30 Lunch
Cultural Excursus Chair: Raphael Berger
13:30 Reinhard Heydenreuter
Penzberg, GE Bavarian history in and around the Chiemsee
14:30 Excursion
Excursion by boat to Herreninsel
19:00 Come together
Reconvening at the Schlosswirtschaft Herrenchiemsee
19:30 Symposium Banquet
(return ca. 23:00)
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Wednesday June 26 Dynamics and Vibration
Chair: Georgii Girichev
9:00 Yuri Tarasov Moscow, RU Intramolecular dynamics and equilibrium structure of non-rigid molecules
9:45 Janne Pesonen Helsinki, FI Vibration and rotation of polyatomic molecules – A geometric algebra approach
10:30 Coffee break
Structural Features of Selected Compound Classes Chair: Nina Giricheva
11:00 Uwe Monkowius Linz, AT Extraordinary temperature dependence of the metal-metal distances in cationic silver(I) complexes bearing
N-heterocyclic carbene ligands
11:30 Jürgen Vogt Ulm, GE New features in the 3D-applet of the forthcoming MOGADOC update
11:50 End of session
12:00 Lunch
13:30 Poster session
Poster Presentations
E. Altova, A. Rykov, L. Khristenko, l. Shishkov
Moscow, RU Molecular structure of α-alanine as studied by gas-phase electron diffraction and quantum chemical calculation
S. Atkinson, S. Masters Christchurch, NZ Development of mass spectroscopy capability with the canterbury gas electron diffraction apparatus
N. Belova, N. Hoang Trang, G. Girichev, H. Oberhammer,
Ivanovo, RU; Tübingen, GE
Tautomeric and conformational properties of acetylacetone, CH3-C(O)-CH2-C(O)-CH3, by gas electron diffraction and
quantum chemical calculations
A.V. Belyakov, Y. Sigo-laev, S. Semenov
St. Petersburg, RU
The silacyclohexanes C5H10SiHCN, C5H10SiH(t-Bu), C5H10Si(t-Bu)CN and C5H10SiHF: a DFT study
A. Bunev, V. Statsyuk, G. Ostapenko
Togliatti, RU Calculating accurate 13
C chemical shifts of azines with density functional methods and modest basis sets
A. Bunev, V. Statsyuk, G. Ostapenko
Togliatti, RU Quantum-chemical investigation of the structure and conformational dynamics amidrazones some azoles
N. Giricheva, N. Belova, M. Fedorov
Ivanovo, RU Heterocyclic aromatic N-Oxides: the nature of semipolar N→O bond and reactive behavior
N. Giricheva, G. Giri-chev, V. Petrov, M. Dak-kouri V. Petrova, S. Ivanov
Ivanovo, RU; Tübingen, Ulm, GE
The structure of 1-naphthalenesulfonyl chloride by gas electron diffraction and quantum chemical calculations
N. Giricheva, V. Petrov, H. Oberhammer, V. Pet-rova, M. Dakkouri, S. Ivanov, G. Girichev
Ivanovo, RU; Tübingen, Ulm, GE
Gas-phase electron diffraction and quantum chemical study of 1-naphthalenesulphonyl fluoride and chloride molecular
structure
N. Giricheva, M. Fedo-rov, S. Ivanov, G. Giri-chev
Ivanovo, RU The electronic and geometric structure of the benzenesulfonic acid methyl ester and its 2- and 4-nitro-substituted molecules
N.Giricheva, M. Fedo-rov, S. Ivanov, G. Giri-chev
Ivanovo, RU Substituent effect on the geometric and electronic structure of benzenesulfonic acid
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Z. Glassman, B. Giro-dias, R. Mawhorter, T. Steimle, M. Jahn, J.-U. Grabow
Claremont, Tempe, USA; Hannover, GE
Electron-nucleus overlap & parity-violating effects in PbF, YbF and RbF
D. Hnyk, D. Wann, H. Robertson, P. Lane, T. Baše, J. Holub
Husinec-Řež, CZ; Edinburgh, GB
Boron-based icosahedra: the structural conse-quences of functionalising the cluster atoms, and their removal
A.A. Ischenko
Moscow, RU Electron diffraction: structure and dynamics of free molecules and condensed matter
I.V. Kochikov, L.S. Khaikin, D.S. Tikhonov, O.E. Grikina
Moscow, RU Analysis of electron diffraction data for 1,3,5-trinitrobenzene molecule with consideration of equivalence of large amplitude
motion coordinates
I. Kolesnikova, O. Doro-feeva, I. Shishkov, I. Hargittai
Moscow, RU; Budapest, HU
Gas-phase electron diffraction and quantum chemical investigation of the molecular structure of benzamide
I. Kolesnikova, O. Do-rofeeva, I. Shishkov, A. Rykov, N. Karasev, H. Oberhammer
Moscow, RU; Tübingen, GE
Molecular structure and conformation of 1,3,5-tris(trifluoro-methyl)-benzene as studied by gas-phase electron diffraction
and quantum chemical calculations
N. Kuze, A. Ishikawa, Y. Ono, H. Takeuchi, S. Konaka
Tokyo, Sapporo, JP
Large-amplitude motions for methyl trifluoroacetate and 2,5-dimethylfuran by GED, MW and quantum chemical
calculation
I. Marochkin, N. Vogt, A. Rykov, O. Dorofeeva, J. Vogt, I. Shishkov
Moscow, RU; Ulm, GE
Molecular structure study of some methyl derivatives of uracil by electron diffraction method and high-level ab initio
calculations
O. Pimenov, G. Giri-chev, V. Maizlish
Ivanovo, RU The structure of free copper (II) 2,9,16,23-tetra-tert-butyl-phthalocyanine: preliminary DFT calculations
A. Pogonin, N. Tverdo-va, A. Ischenko, G. Giri-chev
Ivanovo, Moscow, RU
The molecular structure of zinc(II) etioporphyrin-II: a gas-phase electron diffraction and quantum chemical study
K. Siddiqui, G. Corthey, T. Hasegawa, S. Hayes, K. Pichugin, G. Sciaini, R.J.D. Miller, B. J. Whitaker
Hamburg, GE; Leeds, UK
Ab initio calculations of DNA nucleobases and simulation of electron diffraction patterns
V. Sliznev, N. Belova, G. Girichev, O. Pimenov
Ivanovo, RU Molecular structure of thulium tris-dipivaloyl-methanate, Tm(thd)3, by gas electron diffraction (GED) and DFT
calculations
N. Stepanov Moscow, RU Polyad Quantum Numbers in Vibrational Spectroscopy
V. Tyunina, N. I. Giricheva, G. Girichev
Ivanovo, RU Molecular structure of L-tryptophan
J. Vogt, E. Popov, R. Rudert, N. Vogt
Ulm, GE New features in the 3D-applet of the forthcoming MOGADOC update
N. Vogt, N. Karasev, M. Abaev, A. Makurenkov, W. Leikam, J. Vogt, I. Shishkov
Ulm, Langen-bach, GE; Moscow, RU
Modernization of electron diffractometer EMR-100M
N. Vogt Ulm, GE A benchmark study of molecular structure by GED, MW spectroscopy and coupled-cluster calculations
L.A. Zasurskaya, A.E. Obodovskaya
Moscow, RU Comparative analysis of structures of succinimide and its N-derivatives in crystalline and gaseous phases
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Y. Zhabanov, A. Zak-harov, S. Shlykov, M. Islyaikin, G. Girichev
Ivanovo, RU The structure of a thiadiazole-containing expanded heteroaza-porphyrinoid determined by gas-phase electron
diffraction and DFT calculations.
D. Zhang, S. Bayesteh, H. Delsim-Hashemi, T. Gehrke, F. Mayet, G. Moriena, R.J.D. Miller, et. al.
Hamburg, GE; Toronto, CA
REGAE: Towards Ultrafast electron diffraction and dynamic microscopy
15:30 End of poster session
Instrumentation Chair: Sergey Shlykov
15:30 Sarah Masters Canterbury, NZ A game of two halves: machine development and a conformational conundrum
16:00 Paul Lane Edinburgh, UK Towards megavolt electron diffraction in the UK
16:30 Clemens Schulze-Briese
Baden, CH Hybrid pixel detectors for gas-phase electron diffraction
17:00 Werner Leikam Langenbach, GE Electron-optical equipment for GED
17:30 End of session
18:00 Dinner
19:30 Scientific Discussions
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Thursday June 27 Electrons and electronic effects
Chair: Natalya Belova
9:00 Jan Dillen Stellenbosch, SA Congested molecules: where is the steric repulsion?
9:30 Anna Rita Campa-nelli, Aldo Domeni-cano
L'Aquila, IT
Roma, IT
Transmission of electronic substituent effects through a chain of conjugated double bonds: a quantum chemical study
10:00 Richard Mawhorter Claremont, US Molecules and the electron's electric dipole moment
10:30 Coffee break
Progress in Structural Analysis Chair: Sarah Masters
11:00 Yury Vishnevskiy Bielefeld, GE Development of refinement procedures in gas electron diffraction
11:30 Alexander
Zakharov
Ivanovo, RU Moleculare structure of magnesium octa(m-trifluoromethyl-phenyl) porphyrazine and application of molecular dynamics
for computation of vibrational corrections 12:00 End of session
12:15 Lunch
Associates and Dynamics Chair: Igor Shishkov
14:00 Stuart Young Edinburgh, UK Gas-phase studies of weakly associated species
14:30 Matthew Robinson Edinburgh, UK Pulse dynamics of the Edinburgh time-resolved electron diffractometer
15:00 Konstantyn Pichugin
Hamburg, GE Structural changes in Si induced via auxiliary layer photoexcitation: A femtosecond electron diffraction study
15:30 Coffee break
(Bio-)Organic Structure Chair: Heinz Oberhammer
16:00 Mauricio Alcolea Palafox
Madrid, ES The use of quantum chemical methods in the design of new antivirals
16:30 Christian Reuter Bielefeld, GE Structural results of small chalcogen organyls
17:00 Dines Christen Tübingen, GE Microwave-Microwave-Double-Resonance spectroscopy of acetone in the exited torsional state
17:30 End of session
18:00 Dinner Presentation of the next symposium venue
Friday June 28 8:00-9:30
Breakfast / Departure
__________________________
Miller, Dwayne – Monday, 9:15 h
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“Making the Molecular Movie”: The Chemists’ Gedanken Experiment Enters the Lab Frame
R. J. Dwayne Miller Max Planck Group for Atomically Resolved Dynamics,
Department of Physics, University of Hamburg, The Centre for Free Electron Laser Science, DESY and
Departments of Chemistry and Physics University of Toronto
One of the grand challenges in science is to watch atomic motions as they occur during
structural changes. In the fields of chemistry and biology, this prospect provides a direct
observation of the very essence of chemistry and the central unifying concept of transition
states in structural transitions. From a physics perspective, this capability would enable
observation of rarefied states of matter at an atomic level of inspection, with similar
important consequences for understanding nonequilibrium dynamics and collective
phenomena. This experiment has been referred to as "making the molecular movie". Due
to the extraordinary requirements for simultaneous spatial and temporal resolution, it was
thought to be an impossible quest and has been previously discussed in the context of the
purest form of a gedanken experiment. With the recent development of femtosecond
electron pulses with sufficient number density to execute single shot structure
determinations, this experiment has been finally realized (Siwick et al. Science 2003).
Previously thought intractable problems in attaining sufficient brightness and spatial
resolution, with respect to the inherent electron-electron repulsion or space charge
broadening, has been solved. With this new level of acuity in observing structural
dynamics, there have been many surprises and this will be an underlying theme. Several
movies depicting atomic motions during passage through structural transitions relevant to
condensed phase dynamics will be shown (Sciaini et al. Nature, 2009, Ernstorfer et al.
Science 2009, Eichberger et al Nature 2010, Jean-Ruel, J. Phys. Chem. A 2011).
One of the marvels of chemistry and biology is that despite the enormous number of
possible nuclear configurations, chemical processes reduce to a few key modes. The
“magic of chemistry” is this enormous reduction in dimensionality that makes chemical
concepts transferrable. Recent studies using an order of magnitude brighter, rf
compressed, pulses have given the first the first direct atomic view of the barrier crossing
processes and the distillation of chemistry to projections along a few principle reaction
coordinates (Gao et al. Nature 2013). These new developments will be discussed in the
context of developing the necessary technology to study chemical reaction dynamics for
closed quantum systems in the gas phase to open quantum systems with biological
systems representing the extreme limit in system bath couplings affecting reaction
pathways. The overall objective is to directly observe the structure-function correlation in
biomolecules to provide the most fundamental (atomic) basis to rationalize the
evolutionarily optimized topologies of biological systems.
Schooss, Detlef – Monday, 10:00 h
8
Determination of metal cluster structures by Trapped Ion Electron
Diffraction
Thomas Rapps1, Eugen Waldt1, Reinhart Ahlrichs2, Manfred M. Kappes1,2, and Detlef
Schooss1,2
1 Karlsruher Institut für Technologie, Institut für Nanotechnologie, Postfach 3640, 76021 Karlsruhe, Germany, and
2 Karlsruher Institut für Technologie, Institut für Physikalische Chemie, Kaiserstrasse 12, 76128 Karlsruhe, Germany
Physical and chemical properties of clusters are directly related to their structure, the
identification of gas phase structures is therefore a central point in cluster science. To
experimentally determine gas phase structures of size selected cluster ions we use the
trapped ion electron diffraction technique (TIED). Structures are assigned by comparison
of experimental and simulated molecular scattering functions, the latter are calculated from
candidate structures obtained from density functional or semi-empirical calculations.
We report electron diffraction measurements on a set of 55 atom homonuclear transition
metal clusters covering essentially all 3d and 4d elements (M55–, M= Sc-Cu, Zr-Mo, Ru-
Ag). At 95 K in gas phase only four different structural families are found: irregular
icosahedral, polytetrahedral, icosahedral and close packed. Elements with the same bulk
structure generally have a common cluster structure type. The four structure types differ in
the maximum coordination number in analogy to the coordination number in the
corresponding bulk lattice. The structures of four prototypical clusters Cu55–, Ti55
– Fe55–
and Ru55– are discussed.
Shishkov, Igor – Monday, 11:00 h
9
The structure of methoxyfurane and noradrenaline as studied by gas electron diffraction and quantum-chemical calculations
Prof. Igor F. Shishkov Chemistry Department, M. V. Lomonosov Moscow State University, Moscow, Russia
Recently, in the framework of a joint research carried out with our German colleagues, the Laboratory of electron diffraction investigated the molecule structure of 2-methoxyfurane and noradrenaline using the gas electron diffraction method, as well as quantum-chemical calculations. The quantum-chemical calculations predict the existence of two conformers of 2-methoxyfurane: syn and anti (or quasi-anti). The global minimum corresponds to the syn conformer, whereas the anti form is ~ 1 kcal / mol higher in energy.
Syn Anti
The configuration of the form is flat (Cs). The equilibrium structure of the anti form varies significantly when passing from one method of calculation to a different one. The electron diffraction study made it possible to conclude that in the gas phase both conformers are present, with the likely prevalence of the anti form. The spectroscopic data on the structure of norepinephrine and related compounds containing ethanolamine fragment which are available in the literature, point out to two basic configurations of similar molecules: AG and GG. In this case, although the configuration of pyrocatechol fragment affects the energy of the conformer, it has no appreciable effect on its geometrical structure.
noradrenaline GG AG
Our study of the conformational composition of the vaporous noradrenaline indicates that the GG1 conformers predominate. The observed smaller value of the R-factor for the gauche form gives grounds to conclude that the conformers with gauche orientation of the phenyl and amine groups are present in the mixture. The values of the rh1 geometrical parameters for AG1a and GG1a conformers were determined.
This work was supported by the Russian Foundation for Basic Research (Grant No. 11-03-00716-a and 12-03-91330-NNIO)
Girichev, Georgiy – Monday, 11:30 h
10
Combined gas-phase electron diffraction and mass spectrometry: achievements and problems
Georgiy V. Girichev
Ivanovo State University of Chemistry and Technology, 153000 Ivanovo, Engels av. 7, Russia
The combination of gas-phase electron diffraction (GED) and mass spectrometry(MS)
allows to expand the sphere of using GED from the study of the vapour consisted of only
molecular species to the situations characterised by the complicated vapour composition
and dynamically changing vapour in the scattering volume during experiment
The scheme of the device for an GED/MS experiment is given in the Figure. It allows
- carrying out the set of experiments and using some facilities studying molecular structure
by GED;
- control of the vapour composition and dynamics of vapour pressure during all stages of
experiment including the detection of volatile admixtures;
- overheating the vapour for study of thermal expansion of molecules, for thermal
dissociation of oligomers;
- synthesis of needed species in situ by means of chemical reaction between precursors or
by means of dissociation of suitable solid phase or by thermal decomposition of the
sample.
The main problems concern the uncertainty of vapour composition by MS, which are
connected with:
- using the additive scheme of ionization cross section at interpretation of mass spectra;
- dissociative ionization;
- temperature dependence of mass spectrum is similar to vapour composition change;
- detection of short-living species.
Centurion, Martin – Monday, 13:45 h
11
Ultrafast Electron Diffraction from Aligned Molecules
Martin Centurion
University of Nebraska - Lincoln
We have experimentally demonstrated 3D imaging of a symmetric top molecule by using a
femtosecond laser to align the molecules, and a femtosecond electron pulse to capture the
diffraction pattern while the molecules are aligned.1 The 3D structure of the molecule was
retrieved by combining the information from multiple diffraction patterns corresponding to
different projections of the molecule. We are currently working to extend this method to
more complex molecules, and to image structural dynamics on femtosecond time scales.
1 C. J. Hensley, J., M. Centurion, Phys. Rev. Lett. 109, 133202 (2012).
Weber Peter – Monday, 14:30 h
12
Electron and X-ray probes of molecular structure on ultrafast time
scales
Peter M. Weber
Brown University, Providence, Rhode Island, USA, 02806
The ultrafast structural motions of molecules can be observed using diffraction methods or
spectroscopic techniques. The talk reviews the current status of x-ray diffraction
experiments on gaseous samples at SLAC’s LCLS light source. Separately but related,
photoionization – photoelectron spectroscopy out of Rydberg states has been found to be
a superbly capable method to follow structural motions of molecules in real time. The
method is contrasted to diffraction techniques and recent results on several systems are
presented: the isomerization reaction of the quadricyclane/norbornadiene system, and the
charge transfer in dimethylpiperazine. While it is not possible yet to invert the data to
experimentally determine a structure, paths toward making it a structural spectroscopy are
discussed. Interestingly, it is possible to extend the technique into environments at
atmospheric pressures.
Ultrafast time-resolved Rydberg state binding energy spectrum of
dimethylpiperazine showing a very short-lived 3p state (2.2 eV; also inset) and
a long-lived 3s state revealing the signature of charge delocalization dynamics.
Zhang, Dongfang, – Monday, 15:00 h
13
A femtosecond electron diffraction study: Electronically-driven ablation
via highly localized electronic states
Dongfang Zhang1, Masaki Hada1, Julian Hirscht1, Stuart Hayes1, Kostyantyn Pichugin1, Albert Casandruc1, Stephanie Manz1, Regis Y. N. Gengler1, Toshio Seki2, Jiro
Matsuo2,Gustavo Moriena3, German Sciaini1, and R. J. Dwayne Miller1,3
1Max Planck Research Department for Structural Dynamics, Center for Free Electron Laser Science, University of Hamburg, Luruper Chausee 149, 22761 Hamburg, Germany 2Quantum Science and Engineering Center, Kyoto University, Gokasho, Uji, Kyoto 611-
0011, Japan 3Department of Chemistry and Physics, University of Toronto, 80 St. George St., Toronto,
Ontario M5S3H6, Canada
Ultrafast non-thermal melting in semi-metals and semi-conductors has been extensively
studied by femtosecond X-ray and electron diffraction (FED) techniques. The promotion of
valence carriers to the conduction band in such systems is known to lead to highly
delocalized states which, due to their anti-bonding character, provoke to the collapse of
the lattice in the sub-ps timescale. On the other hand, in alkali halides photo excitation
above the band-gap promotes the system to a highly repulsive but rather localized excited
state. This initial state has been known for over a century as the progenitor of lattice
interstitial and vacancy defects involved in the generation of long-lived color-centers1.
Here single-shot time-resolved optical reflectivity and femtosecond electron diffraction
were applied to study the evolution of the ablation process that follows fs-UV-laser
excitation in single crystalline alkali halides. The results reveal fast optical changes
associated with the development of a disordering process and stress that leads to ejection
of neutral fragments and the formation of micron-deep craters. This atypical cold explosion
was found to occur well below the threshold for plasma formation and even the melting
point of the salt. New insights into the very repulsive nature of these highly localized
excited electronic states will be given.
1 K. Tanimura, Phys. Rev. B 2001, 63, 184303
Tsirelson, Vladimir– Monday, 16:00 h
14
Bonding descriptors based on electron density: how does it look now?
Vladimir G. Tsirelson
Mendeleev University of Chemical Technology, Miusskaya Sq., 9, Moscow 125047,
Russia
Concept of bonding, which allows recognizing and classifying the atomic and
molecular interactions, is one of the basic concepts in structural chemistry and solid-state
physics. Semi-classical description of bonding has often led to contradicting mixture of
notions of classical and quantum mechanics, while competitive development of diffraction
and quantum-chemical methods has resulted to a more successive picture of bonding in
molecules and crystals based on the reliable electron density and electrostatic potential.
Correspondingly, new bonding descriptors based on electron density have been
suggested. They allowed to establish which atoms, in terms of electron density, are
chemically bonded and which are not and to quantify the atomic and molecular
interactions. The experimental electron density was also introduced in the DFT formulae: it
allowed extracting the electronic (total, exchange and correlation) energy characteristics
from the X-ray and electron diffraction experiments.
There is a question whether these developments provide new insights into the
nature of atomic and molecular interactions? In search of an answer to this question we
will consider the most recent results dealing with the bonding descriptors based on the
electron density and its derivatives and equally applicable to theoretical and experimental
densities. We will discuss the descriptors which reflect the properties both the atoms and
bonds, all of them are derived by using certain approximations; therefore the limits of their
applicability will be discussed as well.
This work is supported by Russian Foundation for Basic Research, grant 13-03-
00767a.
Morrison, Carole – Monday, 16:30 h
15
Exciting ‘stuff’: modelling photochemical reactions in the condensed
phase. Applications in time-resolved diffraction.
Carole A. Morrison, Michal A. Kochman
School of Chemistry and EaSTCHEM Research School, University of Edinburgh, King’s
Buildings, Edinburgh, EH9 3JJ, UK.
Interpreting the data obtained from time-resolved pump/probe electron diffraction
experiments is challenging, so we have been looking to develop computational modelling
procedures to help with this process. For the solid state, we know that laser-induced
photo-excitation will affect a subset of molecules randomly distributed in the crystal while
the remainder remain in a non-reactive ground state. From a modelling perspective the
problem is therefore how to treat one molecule in a crystal lattice differently to the rest.
We have achieved this aim by adopting a novel implementation of the QM/QM subtractive
paradigm, whereby the reactive molecule is treated using an excited-state quantum
mechanical procedure, such as CASSCF or TD-DFT coupled to a localized basis set,
while the rest of the system is modelled at the DFT level with a delocalized basis set.1 In
this way we can calculate and extract the forces on the atoms. From here we can run
molecular dynamics simulations to model the timescales for photochemical events, or
follow geometry optimisation to obtain a reactive intermediate embedded in a crystal
lattice.
As an illustration of the predictive power of this simulation method, we discuss its
application to the test system of crystalline 7-(2-Pyridyl)-indole.1 We then recount an
investigation into the photocyclization dynamics of 1,2-bis(2,4-dimethyl-5-phenyl-3-
thienyl)perfluorocyclopentene (shown above), where structures generated with the use of
the QM/QM method are compared to electron diffraction data.
1. M. A. Kochman and C. A. Morrison, J. Chem. Theory Comput., 2013, 9, 1182-1192.
Kochman, Michal – Monday, 17:00 h
16
The mechanism of a solid-state photoisomerisation reaction.
Michal A. Kochman, Carole A. Morrison
School of Chemistry and EaSTCHEM Research School, University of Edinburgh, King’s
Buildings, Edinburgh, EH9 3JJ, UK.
Although the solid state may not usually be thought of as an environment suitable for
chemical reactions under mild conditions, several classes of organic compounds in
molecular crystalline form are known to undergo substantial rearrangement under
irradiation with UV light. We discuss the theoretical investigation of one such system,
N-salicylidene-2-chloroaniline,1 by means of the hybrid QM/QM simulation method
introduced in the previous talk.
The cis-enol isomer of this compound exhibits two photoreaction pathways. In the first, the
photoexcited molecule undergoes an intramolecular proton transfer reaction and
subsequently isomerizes to the trans-keto form through a pedal motion, which is to say, a
simultaneous twist around two bonds. The second pathway is non-reactive and leads to
the recovery of the cis-enol isomer. The cis-enol to trans-keto photoisomerisation is
reversible. Following the photoexcitation of a trans-keto molecule, it undergoes a pedal
motion in the same direction as the one involved in the cis-enol to trans-keto
photoisomerisation, leading back to the cis-keto isomer. In the image shown below, the
structure of the system as the trans-keto molecule undergoes the pedal motion is overlaid
on the experimental crystal structure.
1. M. A. Kochman, A. Bil and C. A. Morrison, Phys. Chem. Chem. Phys., in press.
Scheschkewitz, David – Tuesday, 9:00 h
17
Siliconoids: Stable Unsaturated Molecular Silicon Clusters
David Scheschkewitz
Chair for General and Inorganic Chemistry, Saarland University, D-66125 Saarbrücken
The Si=Si bond of disilenes is a suitable molecular model for the most prominent
characteristic of the reconstructed Si(001)-2x1 surface, the ‘buckled dimer’ I.1 This double
bond and similarly surface-protruding features are pivotal to the expansion of silicon
structures, e.g. via surface bonded rings such as II. In addition, nucleation in chemical
vapour deposition techniques is known to proceed via unsaturated species such as
disilenes, small rings, and (partially) substituted silicon clusters.2 The entry to the
preparative modelling of such processes was provided by the disilenide 1 (R = 2,4,6-
iPrC6H2), inter alia allowing for the isolation of a highly chlorinated cyclotrisilane 2.
Reduction of 2 affords 3, an isomer of the still elusive hexasilabenzene, which exhibits a
novel type of aromatic stabilisation that we refer to as dismutational aromaticity.3
The unprecedented structural and electronic features as well as preparative possibilities of
3 will be discussed. This includes access to other stable unsaturated silicon clusters.4 We
recently coined the term “siliconoids” for this novel compound class.5 Finally, the reactivity
of siliconoids with a view to cluster expansion and contraction will be disclosed.
1 Review: J. Yoshinobu, Prog. Surf. Sci. 2004, 77, 37. 2 Example: E. W. Draeger et al., J. Chem. Phys. 2004, 120, 10807. 3 K. Abersfelder, A. J. P. White, H. S. Rzepa, D. Scheschkewitz, Science 2010, 327, 564. 5 K. Abersfelder, A. J. P. White, R. J. F. Berger, H. S. Rzepa, D. Scheschkewitz, Angew. Chem. Int. Ed. 2011, 50, 7936. 6 K. Abersfelder, A. Russell, H. S. Rzepa, A. J. P. White, P. R. Haycock, D. Scheschkewitz, J. Am. Chem. Soc. 2012, 134, 16008.
Arnason, Ingvar – Tuesday, 9:45 h
18
Properties of monohalogenated silacyclohexanes (CH2)5SiHX; X = F, Cl, Br, I
Ingvar Arnason,a Ágúst Kvaran,a Sigridur Jonsdottir,a Sunna Ó. Wallevik,a Katrin L.
Sigurdardottir,a Ragnar Bjornsson,b Alexander V. Belyakov,c Alexander A. Baskakov,c
Thomas Kern,d Karl Hassler,d and Andras Bodie
aScience Institute, University of Iceland, bMax-Planck Institute for Chemical Energy
Conversion, D-45470 Mülheim an der Ruhr, Germany, cSaint-Petersburgh State
Technological Institute, Saint-Petersburgh 190030, Russia, dTechnische Universität Graz,
Stremayergasse 16, A-8010 Graz, Austria, dPaul Scherrer Institute, 5232 Villigen PSI,
Switzerland
The molecular structure of axial and equatorial conformers of cyclo-C5H10SiHX (X = Cl, Br,
and I), as well as the thermodynamic equilibrium between these species was investigated
by means of gas electron diffraction (GED), dynamic nuclear magnetic resonance
(DNMR), temperature-dependent Raman spectroscopy, and quantum chemical calcu-
lations (QC) applying CCSD(T), MP2, and DFT methods. In all cases the axial conformer
is preferred over the equatorial one. When the experimental uncertainties are taken into
account, all experimental and theoretical results for the conformational energy (axial–
equatorial) for the three molecules fit into a remarkable narrow range of –0.50 ± 0.15 kcal
mol–1. The conformational energies for C6H11X and cyclo-C5H10SiHX (X = F, Cl. Br, I, and
At) were compared using CCSD(T) calculations. Preliminary results from Imaging
photoelectron photoion coincidence spectroscopy with velocity focusing electron optics
(IPEPICO) experiments and computer simulations of the dissociative photoionization
process will be introduced.
Shlykov, Sergey – Tuesday, 10:10 h
19
The molecular structure and conformation properties of 1-phenyl-1-
silacyclohexane
Sergey A. Shlykov and Dmitry Yu. Osadchiy
Ivanovo State University of Chemistry and Technology,
Research Institute for Thermodynamics and Kinetics of Chemical Processes,
Engels ave., 7, 153000 Ivanovo, Russia
1-Pheny-1-silacyclohexane was studied by quantum chemical calculations. Four
possible conformers were considered – with orthogonal and coplanar mutual orientations
of phenyl silacyclohexane rings in axial and equatorial positions of the phenyl substituent.
Relative total energies and free Gibbs energies are noticeably different as estimated
by the methods/basis sets applied (Fig. (a) and (b)). The same may be noticed for the
phenyl group rotation barrier (Fig. (c) and (d), dihedral angle Θ is zero at coplanar
orientation of the rings).
Eq_Orthog Eq_Compl Ax_Orthog Ax_Compl
-0.5
0.0
0.5
1.0
1.5
E, k
cal/
mo
l
DFT/6-31G**
DFT/6-311G**
DFT/cc-pVTZ
MP2/6-311G**
CAM-B3LYP/ (cc-pVTZ)
MP2/cc-pVTZ
RT
Conformer
(a)
Eq_ Orthog. Eq_ Compl. Ax_ Orthog. Ax_ Compl.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
G(2
98 K
), k
cal/
mol
Conformer
DFT/6-31G**
DFT/6-311G**
DFT/cc-pVTZ
MP2/6-311G**
CAM-B3LYP/ (cc-pVTZ)
(b)
-150 -100 -50 0 50 100 150
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
E, kca
l/m
ol
, degrees
B3LYP/ (6-311G**)
B3LYP/ (cc-pVTZ)
MP2/ (6-311G**)
MP2/cc-pVTZ
MP2(FULL)/6-311G**
Axial
RT
(c)
-100 -50 0 50 100
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
E, kcal/
mol
, degrees
B3LYP/6-311G**
B3LYP/cc-pVTZ
MP2/6-31G**
MP2/6-311G**
MP2(FULL)/6-311G**
Equatorial
(d)
Kovács, Attila – Tuesday, 11:00 h
20
Bond length contraction in actinide compounds
Attila Kovács, Peter Pogány, Rudy J. M. Konings
European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O.
Box 2340, 76125 Karlsruhe, Germany
One of the most important structural features of f-elements is the systematic contraction of
their neutral and ionic radii along the lanthanide/actinide row of the periodic system1 due to
the poor shielding of nuclear charge by f electrons. This results in the valence s (6s and 7s
in lanthanides and actinides, respectively) electrons drawn towards the nucleus, thus
leading to smaller atomic and ionic radii.
The contraction can be expected in the compounds of f-elements with strong ionic
character, where the bond lengths are determined by the ionic radii. In compounds with
considerable covalent character the bond lengths are influenced by the molecular orbital
interactions, too.
Recently we performed systematic theoretical studies on several groups of actinide
molecules: AnO, AnO2 (An = Th–Lr),2 AnC2 (An = Th, U, Pu, Am)3 and AnCl3 (An = Th–
Cm). In our presentation the characteristic geometrical features found in the four series will
be shown. The variation of the bond lengths along the actinide row are explained on the
basis of the ionic vs covalent characters and molecular orbital interactions.
1 N. M. Edelstein, J. Fuger, J. J. Katz, L. R. Morss, Summary and Comparison of Properties of the Actinide and Transactinide Elements. In The Chemistry of the Actinide and Transactinide Elements, N. M. Edelstein, J. Fuger, L. R. Morss, Eds. Springer: Dordrecht, 2006; Vol. 3, pp 1753–1835. 2 A. Kovács, P. Pogány, R. J. M. Konings, Inorg. Chem. 2012, 51, 4841–4849. 3 P. Pogány, A. Kovács, D. Szieberth, R. J. M. Konings, Struct. Chem. 2012, 23, 1281–1289.
Pogány, Peter – Tuesday, 11:25 h
21
Structural properties of actinide di- and tetracarbides
Peter Pogánya, Attila Kovácsa,b,Rudy J. M. Koningsa
aEuropean Commission, Joint Research Centre, Institute for Transuranium Elements,
P.O.Box 2340, 76125 Karlsruhe, Germany
bDepartment of Inorganic and Analytical Chemistry, Budapest University of Technology
and Economics, Szent Gellért tér 4., H-1111 Budapest, Hungary
DFT (B3LYP) and CASPT2 calculations were performed on actinide (Th, U, Pu, Am) di-
and tetracarbides. We performed a thorough search for the possible structural isomers of
these compounds, and determined their energetic, bonding and spectroscopic properties.
Five different structures were investigated for AnC2 and twelve structures for AnC4. The
most stable structures have symmetric triangular (1) and fan-like (2) character for di- and
tetracarbides, respectively.
(1) (2) (3) (4)
Some higher energy structures were also studied, since some linear dicarbides (4) were
found in Ar and Ne matrix isolation experiments, whereas the thermodynamically more
stable triangular structure (1) was not found. In case of ThC2 and ThC4 the DFT methods
predicted geometries significantly different what was found with CASPT2, however after
performing wavefunction stability investigations the ground state was identified. The
biggest difference was observed in case of ThC2, where DFT and some single referent HF
and post-HF methods gave asymmetric triangular structure (3) as minimum. After
changing the electronic configuration symmetric triangular (2) structure was found with
most of other methods. The IR frequencies of the investigated structures were also
determined.
P. Pogány, A.Kovács, Z. Varga, F. M. Bickelhaupt, R. J. M. Konings, J. Phys. Chem.,
2012, 116, 747–755.
P. Pogány, A. Kovács, D. Szieberth, R. J. M. Konings, Struct. Chem., 2012, 23, 1281–
1289.
Lokshin, Boris + Ezernnitskaya, Mariam – Tuesday, 11:50 h
22
Spectroscopic and photochemical studies of substituted cymantrenes
Mariam Ezernitskaya, Boris Lokshin, Elena Kelbysheva, Tatyana Strelkova, Yurii Borisov,
and Nikolay Loim
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences
28 Vavilova str. 119991 Moscow, Russian Federation
We report photochemical properties and photochromism of monosubstituted derivatives of
cymantrene containing in the substituent n-donating (carbamate, amide, pyridine) and -
donating (allyl, propargyl) groups capable of forming intramolecular chelates with the
manganese atom in the 16e intermediate formed upon irradiation. In the course of
irradiation the color of solution changed to crimson. In the dark reaction in the presence of
CO the color restored and the parent compound was formed. The structure and properties
of these chelates were elucidated from UV-vis, IR, NMR spectra and confirmed by DFT
calculations. For compounds containing in the substituent amide groups, stable
photochromic systems were obtained in a high quantum yield and fast dark response,
which could stand many cycles without decomposition. In the case of compounds
containing two functional groups (for example, pyridine and allyl), two chelates were
simultaneously formed upon irradiation, and dark reaction was slow and occurred at the
expense of intramolecular linkage isomerisation even in the absence of CO. The influence
of the nature of the donor group and its position in the substituent on the thermodynamic
stability of the chelates formed and their photochemical behaviour is discussed.
Heydenreuter, Reinhart – Tuesday, 13.30 h
23
Prof. Dr. Reinhart Heydenreuter
„Bavarian history
in and around
Chiemsee“
Tarasov, Yury – Wednesday, 9:00 h
24
Intramolecular dynamics and equilibrium structure of non-rigid
molecules: 2-Nitroethanol.
Dmitry Kovtun, Igor Kochikov, Arkady Ivanov, Yury Tarasov
M.V. Lomonosov Moscow State University, 119991, Moscow, Russia
M.V. Lomonosov Moscow State University of Fine Chemical Technologies, 119571,
Moscow, Russia
2-Nitroethanol molecule has been studied earlier by spectroscopic and QC methods1-3.
Conformation but not structural parameters of this molecule were determined
experimentally.
In our study results of combined analysis of GED intensities, vibrational frequencies1 and
rotational constants2 accompanied with QC calculations are reported based on the
treatment given in 4.
The most stable rotamer with hydrogen bonding
is shown in the Figure. The final structural results
are presented in the Table. Values in parentheses are 3σ, upper indexes denote
parameters optimized in groups. The barrier height was evaluated as 500±300 cm-1.
1 P.A. Giguère, T. Kawamura, Can. J. Chem. 1971, 49, 3815. 2 K. M. Marstokk, H Møllendal, Acta Chem. Scand. 1996, 50, 505.
3 T. Varnali, I. Hargittai, J. Mol. Struct. (Theochem), 1996, 388, 315.
4 I. V. Kochikov, Yu. I. Tarasov, N. Vogt, V. P. Spiridonov, J. Mol. Struct. 2002, 607, 163.
MP2/cc-
pVTZ
GED+IR+
MW+QC
re(С-N), Å 1.496 1.500(3) a
re(C-C), Å 1.511 1.515(3) a
re(C-O), Å 1.410 1.414(3) a
re(N-O3), Å 1.232 1.231(2) b
re(N-O4), Å 1.225 1.224(2) b
e ONO, ° 125.2 125.2(0.3)
e NCC, ° 112.3 111.8(0.7)
e CCO10, ° 112.9 112.5(0.7)
Pesonen, Janne – Wednesday, 9:45 h
25
Vibration and rotation of polyatomic molecule – A geometric algebra
approach
Janne Pesonen
Department of Chemistry, University of Helsinki, P.O. BOX 55, FIN-00014 Helsinki,
Finland
In order to model the vibration-rotation spectra of polyatomic molecules, and the
corresponding wave functions in spectroscopic accuracy, one needs to set up the
molecular Hamiltonian as exactly and yet as intuitively as possible. In practice, this means
using some geometrically defined internal coordinates (such as bond lengths, bond angles
and torsion angles), and using an explicitly defined body-frame, in contrast to the old
approach of using normal coordinates and Eckart frame. The (theoretically) most difficult
problem is to obtain the proper representation of the kinetic energy operator, especially its
Coriolis part. These difficulties are easily overcome by the recently developed geometric
(Clifford) algebra approach to kinetic energy operators1. Unfortunately, this methodology is
still not as widely known as it should be.
1 J. Pesonen, L. Halonen, Recent advances in the theory of vibration-rotation
Hamiltonians. Adv. Chem. Phys. 2003, 125, 269–348.
Monkowius, Uwe – Wednesday, 11:.00 h
26
Extraordinary temperature dependence of the metal-metal distances in
cationic silver(I) complexes bearing N-heterocyclic carbene ligands
Margit Kriechbaum,a Johanna Hölbling,a Christa Hirtenlehner,a Georg Stammler,b
Raphael J. F. Berger,*c and Uwe Monkowius*a
aInstitut für Anorganische Chemie, Johannes Kepler Universität Linz, Altenbergerstr. 69, 4040 Linz, Austria; E-mail: [email protected]; bLehrstuhl für Anorganische Chemie und Strukturchemie, Universität Bielefeld, Universitätsstr. 15, 33615 Bielefeld, Germany cMaterialwissenschaften und Physik, Abteilung Materialchemie, Paris-Lodron Universität Salzburg, Hellabrunner Str. 34, 5020 Salzburg, Austria; E-mail: [email protected]
Metallophilic closed-shell interactions are an established concept in coordination chemistry
of coinage metals with formal electronic nd10 configurations. They are most prominent for
linear two-coordinate Au(I) compounds with binding energies of the order of hydrogen
bonds, and less pronounced for the lighter congeners Ag(I) and Cu(I).
In this contribution, we will present a strong temperature dependence of the Ag–Ag
distances in Ag(I) complexes bearing N-heterocyclic carbenes (NHCs). NHC-Ag(I)
complexes are versatile NHC transfer agents and a plethora of compounds has been
reported. Complexes of the form [(NHC)2Ag]A (A = non-coordinating anion) are formed by
the reaction of Ag2O and the respective imidazolium salt. In the case of small substituent
on the NHC-ligand, complexes with Ag–Ag con-
tacts are formed. For the iso-propyl substituted
NHC ligand, the complex [(NHC)2Ag]PF6 features
an alteration of the Ag–Ag bond length of up to 10
% in the temperature range of 100–293 K, which is
more than the “colossal thermal expansion” of the
Prussian Blue analogue Ag3[Co(CN)6].1 We ascribe
this behaviour to a highly anharmonic, flat potential
of argentophilic interactions and proved this hypo-
thesis by means of quantum-chemical interaction
on a suitable model system.
1 A. L. Goodwin et al. Science 2008, 319, 794.
Vogt, Jürgen – Wednesday, 11:30 h
27
New features in the 3D-applet of the forthcoming MOGADOC update
J. Vogt, E. Popov, R. Rudert, and N. Vogt
Chemical Information Systems, University of Ulm, 89069 Ulm, Germany
The MOGADOC database (Molecular Gas-Phase Documentation) has been grown up to
11,500 inorganic, organic, and organometallic compounds, which were studied by in the
gas-phase by microwave spectroscopy, radio astronomy and electron diffraction. The
database contains about 9,000 numerical datasets with internuclear distances, bond an-
gles and dihedral angles. Most of the corresponding molecular structures are also given as
3D presentation (ball-stick-models). The retrieval features of the HTML-based database
have been described elsewhere in details. Some years ago a Java-based applet has been
developed, which enables the 3D-visualization of the molecular structures. The user can
interactively rotate, shift and scale the 3D-models, can “measure” bond lengths as well as
bond, dihedral and elevation angles1.
Recently new “measurement” features have been supplemented (such as for distances
between centroids, angles between ring planes etc.).
The project has been supported by the Dr. Barbara Mez-Starck Foundation, Freiburg
1 N. Vogt, E. Popov, R. Rudert, R. Kramer, and J. Vogt, J. Mol. Struct. 2010, 978, 201
Masters, Sarah – Wednesday, 15:30 h
28
A Game of Two Halves: Machine Development and a
Conformational Conundrum
Christopher O. Burn, Sandra J. Atkinson and Sarah L. Masters
Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch 8140,
New Zealand, [email protected]
This talk will be presented in two parts. The first part will deal with the development of
mass spectrometric capability with the Canterbury gas electron diffraction (GED)
apparatus, the options available to us, and progress thus far. We will also discuss the
planned technical upgrades for the apparatus. The second part will deal with the
conformational conundrum presented by a sterically loaded phosphine. The steric loading
and subsequent effect on geometry of phosphines is of interest to both structural chemists
and synthetic chemists who use these ligands in preparative methods. The gaseous
molecular structures of various sterically loaded phosphines have been investigated,
including bis(trichlorosilyl)tert-butylphosphine,1 bis(tert-butyl)trichlorosilylphosphine2 and
tri(tert-butyl)phosphine.3 In current work the gaseous molecular structure of isopropyl-tert-
butyl-trichlorosilylphosphine (PButPriSiCl3) has been investigated experimentally using
GED and computationally using ab initio and density functional theory (DFT) methods.
Several conformers were predicted for the structure via computational methods. Whilst all
methods predicted the existence of six conformers on the potential energy surface, there
was a lack of agreement between methods on the energy ordering of these conformers.
Can we use the experimental data to guide us when deciphering the energy ordering of
these conformers, or will the conformational conundrum of this asymmetric phosphine
remain unsolved?
1 S. L. Hinchley, H. E. Robertson, D. W. H. Rankin,W.-W. du Mont, J. Chem. Soc., Dalton Trans. 2002, 3787. 2 W.-W. du Mont, L. Müller, R. Martens, P. M. Papathomas, B. A. Smart, H. E. Robertson and D. W. H. Rankin, Eur. J. Inorg. Chem. 1999, 1381. 3 H. Oberhammer, R. Schmutzler and O. Stelzer, Inorg. Chem. 1978, 17(5), 1254.
Lane, Paul – Wednesday, 16:00 h
29
Towards megavolt electron diffraction in the UK
Paul D. Lane, Adam Kirrander and Derek A. Wann
School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, UK EH9 3JJ
Julian W. McKenzie, Mark Surman, Jim Clark and David M. P. Holland
STFC Daresbury Laboratory, Warrington, UK WA4 4AD
We are in the process of developing megavolt electron diffraction in the UK using the 5
MeV electron source VELA (formerly the electron beam test facility) at Daresbury
laboratory. Such facilities exist elsewhere in the world,1,2 but are not currently available in
the UK. This facility would allow electron diffraction studies to be performed with sub-100-
fs electron pulses3 as, by employing relativistic electrons, the space-charge broadening
that is problematic for table-top experiments becomes negligible. Also, the high number of
electrons per pulse could make single-shot time-resolved experiments possible. This
combination would allow the observation of structural changes on the timescales that are
important for chemical processes.
In this work we look at the key electron beam characteristics and experimental geometries,
and simulate a complete experiment to determine the quality of diffraction data that could
be expected from the facility.
1 J. B. Hastings, F. M. Rudakov, D. H. Dowell, J. F. Schmerge, J. D. Cardoza, J. M.
Castro, S. M. Gierman, H. Loos and P. Weber, Appl. Phys. Lett. 89, 184109 (2006).
2 P. Musumeci, J. T. Moody and C. M. Scoby, Ultramicroscopy 108, 1450 (2008).
3 J. W. McKenzie, D. Angal-Kalinin, J. K. Jones and B. L. Militsyn, Proceedings of
IPA2012, 1560 (2012).
Schulze-Briese, Clemens – Wednesday, 16:30 h
30
Hybrid pixel detectors for gas phase electron diffraction
Clemens Schulze-Briese on behalf of DECTRIS
DECTRIS Ltd., Neuenhoferstrasse 107, 5400 Baden, Switzerland
Hybrid pixel detectors have the potential to transform the detection of electrons in a similar
manner as they have transformed synchrotron research by enabling new data acquisition
modes and even novel experiments. During the last years prototype experiments have
been carried out to demonstrate their potential in electron microscopy [1], electron
diffraction [2] as well as low energy electron detection [3].
PILATUS [4] hybrid pixel detectors, first introduced in 2007, have completely changed the
way X-rays are detected. Data quality has improved due to the noise-free operation and
the direct conversion of the X-rays, while millisecond readout time and high-frame rates
allow for hitherto unknown data acquisition speed and efficiency.
The modular architecture and the vacuum-compatibility of the detector modules are ideal
prerequisites to design specific detector solutions with properties well beyond those of the
standard models. In-vacuum operation is ideally suited to eliminate all background arising
from windows and air, resulting in optimal signal-to-noise ratio. Furthermore, the lowest
experimental energy is no longer limited by windows and air absorption but rather by the
beamline spectrum and the detector. The minimal X-ray energy compatible with noise-free
counting for the PILATUS is below 2 keV.
Here we present the prospects of using PILATUS and EIGER [5] detectors in gas phase
electron diffraction experiments. In particular the EIGER detector with its pixel size of 75
µm and module dimensions of 1024 by 512 pixels seems to be well adapted to the
experimental requirements. The detector features continuous readout with a dead time of
only 3 µs. For a detector consisting of 8 modules with an area of approximately 16 by 15
cm2 frame rates of up to 750 Hz can be achieved. The count rate per pixel can be as high
as 2·106 electrons/second.
1 G. McMullan et al., Ultramicroscopy. 2009, 109, 1126 2 D. Georgieva, et al., JINST 2011 6 C01033 3 R. van Gastel et al., Ultramicroscopy. 2009, 109, 111 4 P. Kraft, et al., J. Synchrotron Rad. 2009, 16, 368 5 R. Dinapoli et al., NIM A. 2011, 650(1), 79
Leikam, Werner – Wednesday, 17:00 h
31
Electron-optical equipment for GED
Werner Leikam
Staib Instruments GmbH, D-85416 Langenbach Hagenaustr. 22
In recent years Staib Instruments has delivered electron-sources to replace the original
source of the Balzers Eldigraph KD-G21,2. On this basis an advanced electron optical
column for GED will be presented. The column is intended for routine GED-analysis. The
adjustment of the column is achieved only by electronic means. Disturbances which
reduce the resolution of the GED will be discussed.
1 W. Zeil, J. Haase, L. Wegmann, Z. Instr.1966, 74, 84 2 R. J. F. Berger, M. Hoffmann, S. A. Hayes, N. W. Mitzel, Z. Naturforsch. 2009, 64b, 1259
Dillen, Jan - Thursday, 9:00 h
32
Congested Molecules – Where is the Steric Repulsion?
Jan Dillen
Department of Chemistry and Polymer Science, Stellenbosch University
Private Bag X1, Matieland 7602, South Africa
The computed electron density of several congested saturated hydrocarbons and
halogenated derivatives has been analysed by the method of Interacting Quantum Atoms
(IQA).1 For all the molecules studied, the calculations show the existence of a bond path
between the congested atoms and which, according to the Quantum Theory of Atoms in
Molecules (QTAIM),2 indicates that there is a stabilising interaction between these atoms.
The bond path is found to exist up to inter-atomic distances well beyond the sum of the
Van der Waals radii.
The IQA results indicate that steric hindrance is not a repulsive force between the
congested atoms, but that is the result of an increase in the intra-atomic or self-energy of
the congested atoms. This increase in self-energy is caused by the deformation of the
atomic basin of the congested atoms.
Molecular graph, critical points, and atomic volume of one of the congested hydrogen
atoms in tetracyclododecane as a function of the HH distance.
In all the molecules, and within the range of molecular deformations used in this study, the
increase in self-energy of the atoms has no influence on the presence of a bond path
between the congested atoms. Neither has the fact whether the pair wise interaction
between the congested atoms as calculated with IQA is attractive or repulsive, an
influence on the existence of that bond path.
Based on the results of this study, one has to conclude that neither bond paths, nor
individual pair wise interaction energies as calculated with the IQA formalism, are useful
indicators for the existence or absence of steric hindrance.
1 M.A. Blanco, A.M. Pendás, E. Francisco, J. Chem. Theory Comput. 2005, 1, 1096–1109
2 R.F.W. Bader, Atoms in Molecules: A Quantum Theory, 1990, Oxford, University Press
Campanelli, Anna Rita + Domenicano, Aldo, - Thursday, 9:30 h
33
Transmission of electronic substituent effects through a chain of
conjugated double bonds: a quantum chemical study
Anna Rita Campanellia and Aldo Domenicanob
a Department of Chemistry, Sapienza University of Rome, 00185 Rome, Italy b Department of Physical and Chemical Sciences, University of L’Aquila, 67100 L’Aquila,
Italy
The transmission of electronic substituent effects through a chain of conjugated
double bonds has been investigated by analysing the structural variation of a phenyl
probe induced by a variable substituent X in four series of molecules, Ph(CH=CH)nX
with n = 14. For each series the structures of 46 molecules have been determined by
MO calculations at the B3LYP/6-311++G** level of theory, imposing all-trans
conformation and Cs symmetry.
As in our previous studies of other hydrocarbon frameworks,1 the structural
variation of the phenyl probe is represented by a linear combination of the internal ring
angles, termed SF. Multiple regression analysis of SF values using suitable indicators of
electronic substituent effects shows that the structural variation of the phenyl probe is
determined primarily by the following effects (listed in order of decreasing importance):
(i) the field effect, enhanced by field-induced -polarization of the polyenic chain, (ii) a
resonance-induced field effect, caused by the resonance -charges on the C atoms of
the chain, and (iii) the electronegativity effect, which decreases rapidly with distance (it
disappears when n > 2). The relative importance of field versus resonance effects
increases gradually as the chain becomes longer. Direct -electron transfer from the
benzene ring to the chain, or vice versa, due to resonance effects and field-induced -
polarization, is shown to give rise to quadratic terms in the regression.
The SF parameters are closely related to the electron density distribution in the -
system of the molecules. They are well reproduced by a linear combination of the -
charge residing on the C atom of the chain and the absolute value of the -charge
transferred from the benzene ring to the chain, or vice versa.
References
1. A. R. Campanelli, A. Domenicano, Struct. Chem. 2013, 24, DOI 10.1007/s11224-013-0242-0; A. R. Campanelli, Struct. Chem. 2013, 24, DOI 10.1007/s11224-013-0231-3; and references therein.
Mawhorter, Richard – Thursday, 10:00 h
34
Molecules and the electron's electric dipole moment
Richard Mawhorter1, Zachary Glassman1, Benjamin Girodias1,
Trevor Sears2, Chris McRaven2, Lukas Alphei3, & Jens-Uwe Grabow3
1Physics Dept., Pomona College, Claremont, CA 91711 USA
2Chemistry Dept., Brookhaven National Laboratory, Upton, NY 11973 USA
3Institut für Physikalische Chemie, Leibniz-Universität, Hannover D 30167
Polar diatomic molecules
are ideal laboratories for
investigating the effects of
parity non-conservation, and
high resolution microwave
spectroscopy provides a unique
window onto these tiny effects.
These include the nuclear
anapole moment and the
electric dipole moment of the
electron, or eEDM.
Motivated by the ongoing
search for the eEDM and the
opportunity to confirm the lone anapole moment measurement in atomic cesium, rotational
spectra of all 4 isotopologues of the PbF radical (see energy level diagram by Neil Shafer-
Ray) were measured using a supersonic jet Fourier transform microwave spectrometer at
the Leibniz Universität in Hannover. Field-free and Zeeman measurements over a range of
3 - 26 GHz have resulted in the discovery of the near-degeneracy of 2 states of opposite
parity in 207PbF and the determination of 2 new spectroscopic parameters. They further
provide a confirmation of the relative insensitivity of PbF to stray magnetic fields in an
eEDM experiment, as well as a stringent test of the quality of calculated PbF wave
functions. New work on YbF as well as a means to extend the reach of microwave
spectroscopy even further towards the mHz regime of the eEDM will also be presented.
Vishnevskiy, Yuri – Thursday, 11:00 h
35
Development of refinement procedures in gas electron diffraction
Yury V. Vishnevskiy and Norbert W. Mitzel
Bielefeld University, Universitätsstraße 25, Bielefeld, Germany
Traditional procedures for refinement of the molecular structure in the GED method require
definition of molecular geometry in terms of independent internal coordinates. In the stable
version of the UNEX1 program this is done by defining z-matrices for molecules. However,
this approach limits accuracy of refined molecular parameters and hinders automation of
structural analysis. Introduction of the method of predicate observations2 has played an
important role in the development of the GED method and lead to elaboration of the
SARACEN method,3 in which flexible restraints are used instead of fixed constraints.
Nevertheless, this approach still uses independent internal coordinates (bond lengths,
angles, etc.) as parameters to be refined. This, in turn, leads to ambiguity in choosing of
such sets of coordinates and, as a consequence, to a decrease of the real accuracy of
refined the molecular structure. To overcome this problem we have recently developed a
procedure for refinement of molecular geometry in terms of Cartesian coordinates with
additional usage of theoretical data for regularization purposes.4 The first molecule refined
both with new and conventional procedures was 3-methyl-1-boraadamantane. Detailed
analysis of errors of refined parameters proved that the new method outperforms the
traditional one. Our current activity includes the further development of the described
refinement procedure in order to increase accuracy and automation of the GED method in
general.
1 Yu. V. Vishnevskiy, http://unexprog.org
2 L. S. Bartell, D. J. Romenesko, T. C. Wong, Molecular Structure by Diffraction Methods,
The Chemical Society, London, 1975, 3, 72 – 79.
3 N. W. Mitzel, D. W. H. Rankin, Dalton Trans., 2003, 3650 – 3662.
4 Yu. V. Vishnevskiy, M. A. Abaev, A. N. Rykov, M. E. Gurskii, P. A. Belyakov, S. Yu.
Erdyakov, Yu. N. Bubnov, N. W. Mitzel, Chem. Eur. J., 2012, 18, 10585 – 10594.
Zakharov, Alexander – Thursday, 11:30 h
36
Molecular structure of magnesium octakis(m-trifluoromethylphenyl)
porphyrazine and application of molecular dynamics for computation of
vibrational corrections
Alexander Zakharov, Yuriy Zhabanov, Sergei Shlykov and Georgiy Girichev
Ivanovo State University of Chemistry and Technology, Research Institute of Chemistry of Macroheterocyclic Compounds, F. Engels av. 7, Ivanovo 153000, Russian Federation
The gas-phase molecular structure of the magnesium octa(m-trifluoromethylphenyl)
porphyrazine (MgC72H32N8F24) has been studied by a synchronous gas-phase electron
diffraction (GED) and mass
spectrometric experiment and
density functional theory
calculations using the B3LYP
hybrid method and triple-ζ
valence basis sets. The mole-
cule has an equilibrium
structure of D4 symmetry with
almost planar macrocycle (see
the figure). In this study we
applied a method of calcula-
ting vibrational corrections
using molecular dynamics
(MD) simulations, which has
been recently reported.1, 2
This technique has an advan-
tage of directly producing corrections to equilibrium distances, allowing to determine
equilibrium structures from GED data. In the present study we successfully used DFT MD
with the level of theory similar to one utilised in force field computations.
The study was supported by the RFBR, grant no. 13-03-00975. 1 D. A. Wann, R. J. Less, F. Rataboul, P. D. McCaffrey, A. M. Reilly, H. E. Robertson, P. D. Lickiss, D. W. H. Rankin, Organometallics 2008, 27, 4183. 2 D. A. Wann, A. V. Zakharov, A. M. Reilly, P. D. McCaffrey, D. W. H. Rankin, J. Phys. Chem. A 2009, 113, 9511.
Young, Stuart – Thursday, 14:00 h
37
Gas-phase electron diffraction of weakly associated species
Stuart Young, Matthew Robinson, Paul Lane and Derek Wann
University of Edinburgh, Joseph Black Building, West Mains Road, EH9 3JJ
Weakly associated species, such as strong van der Waals interactions, cannot be
efficiently studied using conventional effusive nozzles. Apparatus in Edinburgh has been
adapted to use a supersonic expansion nozzle assembly to vibrationally cool samples,
allowing structural determination of dimers and complementary molecules. Other novel
features of the apparatus include a telefocus gun capable of producing a high intensity
electron beam, needed to view small sample density, and a CCD camera.
Counterpoise calculations have been carried out for pyrazole, pyridine-2-ol, silyl chloride
and silyl iodide dimers as well as complementary pseudo base-pairs. Utilising frequency
calculations, radial distribution curves were simulated at 100 K, showing increased detail
at larger interatomic distances, which would be related to the weak interactions.
Robinson, Matthew – Thursday, 14:30 h
38
Pulse dynamics of the Edinburgh time-resolved electron diffractometer
Matthew S. Robinson, Stuart Young, Paul D. Lane, Derek A. Wann
School of Chemistry, The University of Edinburgh, Joseph Black Building, King’s Buildings,
Edinburgh, EH9 3JJ
We have assembled and tested our new compact time-resolved gas electron
diffractometer. In this talk I will discuss the properties of the diffractometer, and its potential
capabilities, before going on to detail the types of simulations that we have carried out to
determine the properties of the apparatus. We will look at the time-resolution of the
apparatus as a whole, as well as other beam properties at the various points throughout
the electrons’ flight, and how these are affected by the introduction of a magnetic lens to
the apparatus. Comparisons on the efficiency of different particle tracer programs will also
be discussed, including SIMION1 and General Particle Tracer2.
1. D. A. Dahl, SIMION for the personal computer in reflection. Int. J. Mass Spectrom., 200:3-25, 2000.
2. S. B. Van Der Geer and M. J. De Loos, General particle tracer. Elements, 1–202, 2009
Pichugin, Kostyantyn – Thursday, 15:00 h
39
Structural changes in Si induced via auxiliary layer photoexcitation:
A femtosecond electron diffraction study
Kostyantyn Pichugin1, Hayes Stuart1, Shelley A. Scott3, Max G. Lagally3, Dongfang Zhang1, Julian Hirscht1, Albert Casandruc1, Masaki Hada1, Germán Sciaini1, and R. J.
Dwayne Miller1;2;*
1 Max Planck Institute for Structure and Dynamics of Matter, Department of Physics,
University of Hamburg, Center for Free Electron Laser Science, DESY, D-22607, Hamburg, Germany.
2 Departments of Chemistry and Physics, University of Toronto, Toronto, Ontario, M5S 3H6, Canada.
3 University of Wisconsin-Madison, Madison, WI 53706, USA * [email protected]
Ultrafast electron diffraction (UED) is an indispensable tool capable of tracking minute
changes in materials structure on the femtosecond timescale. However, in practice time-
resolved studies are often limited to the materials which can be photoexcited within the
range of wavelengths readily available from commercial lasers. Recently, Hada et al. [1]
demonstrated a semiconductor-to-metal phase transition in VO2 driven by hot electrons
photoinjected from an adjacent Au nano-layer. The idea of using non-transparent media as
a secondary source of excited carriers to trigger structural changes in the target material is
of great importance because it offers a general approach to soften the aforementioned
restriction.
In this work we extend the auxiliary excitation source concept to UED experiments. For the
model sample we have chosen a nanocomposite comprised of a 20 nm Al layer deposited
on top of a 49 nm single crystalline Si membrane. Consequently, when the sample is
illuminated with the fundamental of Ti:Sapphire laser the aluminum layer becomes the
major supplier of excited carriers since the silicon material is largely transparent at 800 nm
wavelength. All measurements were conducted with a newly built electron diffraction appa-
ratus that provides sub-picosecond electron bunches at 1 kHz repetition rate. Our prelimi-
nary results for the time dependent series of diffraction patterns reveal several oscillations
with a period of 11 ps corresponding to the longitudinal acoustic wave propagating in Si
film along the surface normal. These findings are in a good agreement with the previous
UED studies which involved direct UV photo-doping in free-standing silicon films [2].
1 M. Hada, D. Zhang, A. Casandruc, and R. J. D. Miller, Phys. Rev. B., 86, 134101, 2012. 2 M. Harb, W. Peng, G. Sciaini, C. T. Hebeisen, R. Ernstorfer, M. A. Eriksson, M. G. Lagally, S. G. Kruglik, and R. J. D. Miller, Phys. Rev. B., 79, 094301, 2009.
Palafox, Mauricio Alcolea - Thursday, 16:00 h
40
The use of quantum chemical methods in the design of new antivirals
M. Alcolea Palafox, and N. Iza
Departamento de Química-Física I, Facultad de Ciencias Químicas
Universidad Complutense, Ciudad Universitaria, Madrid-28040, Spain
The first phosphorylation of the nucleosides analogues by the ATP kinase is a crucial step
in the activity of the prodrugs. The proportion of compound phosphorylated is in general
very small in the mayority of the prodrugs. Thus, for the design of new effective antivirals it
is important to understand this first phosphorilation step. Efficient phosphorylation depends
largely on the spatial structure of the nucleoside. Thus, an extensive conformational
analysis identifying all minima on the potential energy surface can be considered as a first
step. Among the prodrugs, those derivatives of deoxythymidine (R1=CH3, R2=OH, R3=H)
were the most used, Fig. 1. Structures with a hydrophilic group in R2 facilitate opened
clusters with a long O2···O5 distance and easier phosphorylation, i.e. with higher activity.
In different C4 derivatives of D4T (R1=CH3, without R2, R3=H, and with double
bond C2=C3) was observed the following [1]: all the substituents on C4 that produce an
increase in the negative charge on O4, and as consequence on O2 and O4, and increase
of the dipole moment, and low furanose pucker P, increment the activity.
Simulating how the bonding process of D4TTP to viral DNA
in the cavity of the reverse transcriptase enzyme is
observed that substituents in 2-position should be very
small for steric interaction with residue Y115. Substituents
in 4-position can be large, but in 3-position should be
small.
In 5-halogenated derivatives of deoxythymidine (R1=
halogen) [2], a decrease in the calculated dipole moment, a lengthening of the O5’···O2
and O3’···O2 distances, an increment in the NBO negative charge on O2 and on the
halogen atom appear related to a decrease in the activity.
1 M. Alcolea Palafox, N. Iza, J. Mol. Struct. 2013, in press.
2 M. Alcolea Palafox, Struct. Chem. 2013, DOI: 10.1007/s11224-013-0225-1.
Fig. 1
Reuter, Christian – Thursday, 16:30 h
41
Electron diffraction and gas phase structures of several sulphur and nitrogen compounds
Christian G. Reuter, Yury V. Vishnevskiy and Norbert W. Mitzel
Bielefeld University, Universitätsstraße 25, Bielefeld, Germany
We will present details regarding the molecular structures of R-SCN where R can be CCl3,
CCl2F and -CH2Cl determined by means of GED experiments.1 For CCl2F and CH2Cl we
found two conformers each. The gas phase experiments for ClF2C-
C(O)-X with X = CN, NCO and NCS yielded only two conformers for
each the molecules.2,3 We are comparing X-C(O)-NCS, X-C(O)-SCN
(X = Cl, F) where only the Cl species have been refined yet. The
class of R-SNO compounds represented through R = CH3-CH2, CF3-
CH2 and (CH3)3C has also been investigated. Our most recent efforts
have been put into the investigation of CF3-CF2-C(O)-X with X = F,
Cl and I. In the gas phase structure of ClC(NO2)3 an exceptionally
short C-Cl bond has been reported.4,5 To extend this work the Br and
F derivatives were investigated.
Furthermore we present brief news about the Bielefeld experiment showing the progress in
Experiment automation.
1 L. A. Ramos, S. E. Ulic, R. Romano, M. F. Erben Y. V. Vishnevskiy, C. G. Reuter, N. W. Mitzel, H. Willner, H. Beckers, X. Zeng, E. Bernhardt, S. Tong, M. Ge, C. O. Della Védova, et al., J. Phys. Chem. A 2013, 117, 2383–2399.
2 L. A. Ramos, S. E. Ulic, Y. V. Vishnevskiy, N. W. Mitzel, H. Willner, C. O. Della Védova, R. Romano, H. Beckers, S. Tong, M. Ge, submitted.
3 L. A. Ramos, S. E. Ulic, R. M. Romano, S. Tong, M. Ge, Yu. V. Vishnevskiy, R. J. Berger, N. W. Mitzel, H. Beckers, H. Willner, C. O. Della Védova, Inorg. Chem. 2011, 50, 9650.
4 M. Göbel, B. H. Tchitchanov, J. S. Murray, P. Politzer, T. M. Klapötke et al., Nature Chem. 2009, 1(3), 229–235.
5 N. I. Sadova, N. I. Popik, L. V. Vilkov, A. Pankrushev, V. A. Shlyapochnikov, J. Chem. Soc. Chem. Commun. 1973, 3, 708.
Christen, Dines – Thursday, 17:00 h
42
Microwave-microwave-Double-Resonance spectroscopy of Acetone in the excited torsional state, ν17
Dines Christena, Melanie Unratha, Martina Müllera, Susan Obsta and Peter Gronerb
a Institut für Physikalische und Theoretische Chemie der Universität Tübingen, Auf der
Morgenstelle 18, 72076 Tübingen, Germany b Dept. of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499,
USA
Acetone is so commonly known and used that one hardly expects any difficulty handling it.
The handling of the rotational spectrum, however, is difficult and tedious. The reason for
this complication is well known: The two internal rotors. But the analysis of the rotational
spectrum is still complicated, although the Hamiltonian – in principle – is known.
The combination of the symmetry numbers (σ1, σ2) = (0, 0) is non-generate. It
corresponds to the symmetry label AA in the conventional notation. The remaining
combinations form a fourfold degenerate set [(0, 1), (1, 0), (0, 2) and (2, 0)], corresponding
to label EE and two doubly degenerate pairs [(1, 1) and (2, 2)] corresponding to AE and
[(1, 2) and (2, 1)], corresponding to EA.
Because of the interactions, the sub-states have slightly different rotational energy levels.
This leads to rotational transitions split into four different components, one for each sub-
state. For the ground state, the width of this quartet splitting extends from a few MHz to
more than 1 GHz.
The narrowest quartet in ν17 is several hundred MHz wide, with most quartets reaching
several GHz.
Measurements and fits of transitions in the states AA, EE and AE will be presented.
Poster session
43
Molecular structure of α-alanine as studied by gas-phase electron
diffraction and quantum chemical calculation
Ekaterina P. Altova, Anatoly N. Rykov, Lyudmila V. Khristenko, Igor F. Shishkov
Chemistry Department, M.V. Lomonosov Moscow State University, Moscow, Russia
α-Alanine is of significant interest in the different fields of chemistry including structural
investigations. Till now the structure of gaseous α-alanine was investigated using the gas-
phase electron diffraction (GED) method. In an earlier study, the thermal-average structure
by GED1 and the structure by joint analysis using electron diffraction data and rotational
constants2 were determined. The purpose of the present research is the reinvestigation of
the molecular structure of α-alanine by the GED method and the determination of the
equilibrium structure taking into account vibrational corrections calculated from MP2/cc-
pVTZ. Тhe conformational vapour composition of α-alanine was estimated by the relative
Gibbs free energies and then identified by analyzing the GED data. The most stable α-
alanine form is shown in Fig.
This research was supported by the Russian Foundation for Basic Research (project no.
11-03-00716) and the Russian Foundation for Basic Research - Deutsche Forschungs-
gemeinschaft (project no. 12-03-91330).
Fig. The molecular structure of α-alanine
1 K. Iijima, B. Beagley, J. Mol. Struct, 1991, 248, 133.
2 K. Iijima, M. Nakano, J. Mol. Struct. 1999, 485–486, 255.
Poster session
44
Development of Mass Spectroscopy Capability with the Canterbury
Gas Electron Diffraction Apparatus
Sandra J. Atkinson and Sarah L. Masters
Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch 8140,
New Zealand, [email protected]
Recent research in the Canterbury gas electron diffraction (GED) group has focussed on
the investigation of gaseous molecular structures of new species generated in situ, either
by reaction or decomposition of a parent molecule. One side effect of this species
generation method is manifestation of several products of reaction or decomposition in the
vapour for analysis. Current research is focused on modifying the existing Canterbury
GED apparatus to incorporate a mass spectrometer (MS) so synchronous GED / MS data
can be obtained within a single experiment. This poster will focus on the key factors being
taken into consideration in such a design and the current setup concepts being
considered, highlighting the progress made to date.
Poster session
45
Tautomeric and conformational properties of acetylacetone,
CH3-C(O)-CH2-C(O)-CH3, by gas electron diffraction and quantum
chemical calculations
Natalya V. Belovaa, Nguen Hoang Tranga, Georgiy V. Giricheva, Heinz Oberhammerb
a Research Institute for Thermodynamics and Kinetics of Chemical Processes,
Ivanovo State University of Chemistry and Technology, Russia
b Institut für Physikalische und Theoretische Chemie,
Universität Tübingen, Germany
The calculated potential surface (with B3LYP/6-31G(d,p) approximation) for rotation of two
C(O)CH3 fragments in the keto form of acetylacetone possesses only one minimum of
energy corresponding to the (sc,sc) conformer with both τ(OCCC) torsional angles about
900. According to the calculations there is only one stable enol conformer. The predicted
relative energies (Δ(E)=Eketo-Eenol) and relative free energies (Δ(G0)=G°keto–G°enol)
depend strongly on the computational method. Whereas B3LYP/6-31G(d,p), B3LYP/aug-
cc-pVTZ and MP2/cc-pVTZ methods predict a strong preference of the enol tautomer,
MP2/6- 31G(d,p) method predict about 80% of the enol form at room temperature and
nearly equal amount of two tautomeric forms in overheated (671K) vapour.
The electron diffraction patterns and the mass spectra were recorded simultaneously at
two different temperatures of vapour. Analysis of GED intensities result in the presence of
100(3)% enol tautomer at 300(5)K, and of a mixture: 64(5)% enol and 36(5)% keto forms
at 671(5)K. The tautomeric composition at 671(5)K corresponds to a free Gibbs energy
difference Δ(G0)= 0.77(21) kcal/mol, that is surprisingly close to calculated with MP2/6-
31G(d,p) value (ΔG0 = 0.83 kcal/mol). The rh1 parameters of the enol form are very close
for both experimental results as well as for calculated (B3LYP/aug-cc-pVTZ and MP2/cc-
pVTZ) values. The enol ring possesses Cs symmetry with a strongly asymmetric hydrogen
bond.
This work was supported by Russian-German Cooperation Project
(RFBR N 12-03-91333-ННИО_а and DFG OB 28/22-1)
Poster session
46
Silacyclohexanes C5H10SiHCN, C5H10SiH(t-Bu),
C5H10Si(t-Bu)CN, and C5H10SiHF: DFT study
Yurii F. Sigolaev1, Sergei G. Semenov2, and Alexander V. Belyakov1
1 Technological Institute, 190013 Saint-Petersburg, Moskovskii prosp. 26, Russia
2 Saint-Petersburg State University, 198504 Saint-Petersburg, Russia
Titled compounds were studied at the M06-2X/aug-cc-pVTZ level of theory. It is
determined geometrical parameters, dipole moments, polarizabilities, first hyper-
polarizabilities and relative energies of the axial and equatorial conformers. For cyano
group and fluorine atom more preferable is axial position whereas for tert-butyl group
equatorial one. Polarizabilties of conformers are similar but optical anisotropy of equatorial
conformers of C5H10SiHCN and C5H10SiH(t-Bu) molecules is much larger than that of axial
conformers. Upon substitution in nitriles of C1 atom by Si atom hyper-polarizability is
increased by many times.
Poster session
47
Calculating accurate 13C chemical shifts of azines with density
functional methods and modest basis sets
Alexander S. Bunev, Vladimir E. Statsyuk, and Gennady I. Ostapenko
Togliatti State University, 445667 Togliatti, Belorusskaya 14, Russia
The purpose of this report is to convince practitioners of 13C NMR spectroscopy to
consider simple quantum chemical calculations as a viable option to aid them in the
assignment of their spectra. To this end, it is demonstrated, on a test set of 25
conformationally stable molecules azines of various kinds containing different positions the
nitrogen atoms, that, in contrast to what is claimed in the literature, large basis sets are not
needed to obtain rather accurate predictions of 13C NMR chemical shifts by quantum
chemical calculations. On the other hand, modelling the solvent by an SCRF-type
calculation may improve certain predictions significantly.
Exploratory calculations showed clearly that hybrid functionals are more apt to yield
accurate predictions of 13C chemical shifts than pure functionals. We decided to focus on
two groups of them, the popular B3LYP functional and the BLYP, B3PW91, PW1PW91
B98, BMK, HCTH, VSXC, M06, M06x, TPSSh, PBEh, X3LYP, LC-wPBE functionals. We
systematically explored double- and triple-ξ basis sets of the Pople (6-31G(d,p), 6-
31+G(d,p), 6-31++G(d,p), 6-311+G(d,p), 6-311++G(d,p), 6-311++G(2d,p)) and Dunning
families (cc-pVDZ, aug-cc-pVDZ, cc-pVTZ, aug-cc-pVTZ). The magnetic shielding
constants were computed using GIAO and GSGT methods. NMR calculations were carried
out both in the gas phase and in solution, using the polarizable continuum model PCM with
chloroform as the solvent.
Poster session
48
Quantum-chemical investigation of the structure and conformational
dynamics amidrazones some azoles
Alexander S. Bunev, Vladimir E. Statsyuk, and Gennady I. Ostapenko
Togliatti State University, 445667 Togliatti, Belorusskaya 14, Russia
Ab initio quantum-chemical calculations of equilibrium geometric parameters, vibrational
frequencies, and potential of internal rotation of amidrazones (scheme 1, 2) molecules in
their ground (S0) electronic states were performed.
Scheme 1. Structural formulas of conformers amidrazones
-150 -100 -50 0 50 100 150
0
2
4
6
8
10
E, kcal/m
ol
, degress
Scheme 2. The potential curve of internal rotation of amidrazones in S0 state.
Poster session
49
Heterocyclic aromatic N-Oxides:
the nature of semipolar N→O bond and reactive behavior
Nina I. Giricheva a, Natalya V. Belova b, Mikhail S. Fedorov a
a Ivanovo State University, Russia
b Research Institute for Thermodynamics and Kinetics of Chemical Processes,
Ivanovo State University of Chemistry and Technology, Russia
Molecular and electronic structure of some pyridine-N-oxides with -Cl, -CH3, -NO2, -OCH3,
-C2H2-Ph-N(CH3)2, and -C2H2-Ph-OCH3 as the substituents were studied by quantum
chemical calculations (DFT/B3LYP/cc-pVTZ, DFT/PBE0/cc-pVTZ and MP2/cc-pVTZ).
NBOanalysis was applied to description of semipolar N→O bond nature. The calculations
show that the introduction of acceptor (–NO2 substituent) in the molecule of N-oxide leads
to the significant lowering of HOMO and LUMO and, as the result, to growing of oxidation
affinity. The donor substituents (such as –CH3 and –OCH3)
favour the growing of N-oxides reductive properties. In the
molecules with π- conjugation between pyridine ring and the
substituent (-C2H2-Ph-N(CH3)2, and -C2H2-Ph-OCH3) the
LUMO goes down, whereas HOMO grows up, thereby the
excitation energy decreases. NBO-analysis interprets the
bonding σ(N-O) natural orbital as the linear combination of two
atomic hybrid orbitals: σ(N-O) = 0.7h(N)+0.7h(O). Due to the
polarization coefficients are equal, σ(N-O) is covalent bond.
Moreover, oxygen has three lone pairs: LP1= sp0.28, LP2= pπ and LP3 = pσ. There is
strong donor-acceptor interaction between lone pair of oxygen LP2 and anti-bonding π*(N-
C). The π-conjugation between the pyridine ring and LP2(O) provides the charge transfer
from oxygen to the ring. The introduction of strong donor substituent leads to the
lengthening of N→O bond and decreasing of N→O bond order. In this case electron
density on oxygen considerably increases, and complexing reactivity of the substance
grows up.
Poster session
50
Boron-based icosahedra: the structural consequences of
functionalising the cluster atoms, and their
removal
Drahomír Hnyk,a Derek A. Wann,b Heather E. Robertson,b Paul D. Lane,b Tomáš Baše,a
and Josef Holuba
a Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i.,
250 68 Husinec-Řež, Czech Republic.
b School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ,
UK.
Just as carbon forms hydrocarbons, its neighbour, boron, forms boron hydrides. Due to the
electron deficiency of boron, these boron hydrides do not resemble hydrocarbons in terms
of molecular shapes. The geometries of boron clusters are based on various polyhedra,
with the icosahedron being the most prominent. Indeed, closo-B12H122– represents one of
the most important building blocks in boron cluster chemistry and, moreover, is the most
symmetrical geometric arrangement of boron and hydrogen atoms (Ih point-group
symmetry). Departure from this symmetry may be achieved by replacing boron with
heteroatoms, such as carbon, in various positions within the cage, by replacing hydrogen
atoms with a variety of substituents (halogens and SH are often seen), and, finally, by
removing one, two, or more vertices, resulting in further classes of boron clusters, such as
nido or arachno.
Examples derived by substituting carbon atoms into closo-B12H122–, by replacing hydrogen
atoms with other atoms or moieties, and by the removal of the aforementioned carbon
atoms, were studied using gas electron diffraction in conjunction with ab initio and DFT
computational protocols of various quantities. These clusters are the subject of this
presentation.
Poster session
51
The structure of 1-Naphthalenesulfonyl chloride by gas electron
diffraction and quantum chemical calculations
Nina I. Giricheva,# Georgiy V. Girichev§*, Vjacheslav M. Petrov,# Marwan Dakkouri&,
Valentina N. Petrova,§ Sergey N. Ivanov#
#Ivanovo State University, Ivanovo 153025, Russia
§Ivanovo State University of Chemistry and Technology, Ivanovo 153000, Russia
&Department of Electrochemistry, University of Ulm, Germany
a-Naphthalenesulphonyl chloride, a-NaphSCl, was studied by gas-phase electron
diffraction (GED) and quantum chemical calculations (HF/6-311+G**, HF/aug-ccpVDZ,
B3LYP/cc-pVDZ, B3LYP/cc-pVTZ, B3LYP/aug-cc-pVDZ, B3LYP/aug-cc-pVTZ and
MP2/cc-pVDZ, MP2/cc-pVTZ). The calculations predict the existence of two conformers
with _1(I) and _s(II) symmetry. The more stable conformer I possesses an enantiomer.
The calculations showed, that in the vapor under experimental conditions the mole fraction
of conformer II with coplanar position of S-Cl bond and naphthalene frame is not more 1
mol %.
On the basis of the experimental data it was found that the gas phase over a-NaphSC at
370(5) K is represented by molecular species I of C1 symmetry in which the Ca-S-Cl plane
deviates from the perpendicular orientation relative to the naphthalene skeleton plane. The
following geometrical parameters (Å and degrees) of conformer I were obtained from the
experiment (uncertainties are in parantheses): rh1(C-H) = 1.082(6), rh1(C-C)av = 1.407(3),
rh1(C-S) = 1.764(5), rh1(S-O)av = 1.425(3), rh1(S-Cl) = 2.051(5), ÐC-Ca-C = 122.5(1)º,
ÐCa-S-Cl = 101.5(10)º; C9-C1-S-Cl = 71.4(21)°.
The calculated barriers for internal rotation of the sulphonyl chloride group exceed
considerably the thermal energy values corresponding to the temperatures of the GED
experiments. Natural bond orbitals (NBO) analyses of electron density distribution were
applied to explain the peculiarities of the molecular structure of the studied compound and
the deviation from the structures of b-NaphHal molecules and their benzene analogs.
We thank the Deutsche Forschungsgemeinschaft and Russian Fond of Basic
Researches for financial support of the Russian-German Cooperation (grants DFG OB
28/22-1 and RFBR 12-03-91333-HHИO-a)
Poster session
52
Gas-Phase Electron Diffraction and Quantum Chemical Study of b-
Naphthalenesulphonyl Fluoride and Chloride Molecular Structure
Nina I. Giricheva,# Vjacheslav M. Petrov,# Heinz Oberhammer,& Valentina N. Petrova,§
Marwan Dakkouri,d Sergey N. Ivanov,# Georgiy V. Girichev §*
#Ivanovo State University, Ivanovo 153025, Russia
§Ivanovo State University of Chemistry and Technology, Ivanovo 153000, Russia
&Institut für Physikalische und Theoretische Chemie, Universität Tübingen, 72076
Tübingen, Germany
dDepartment of Electrochemistry, University of Ulm, Germany
b-Naphthalenesulphonyl fluoride, b-NaphSF, and b-naphthalenesulphonyl chloride, b-
NaphSCl, were studied by gas-phase electron diffraction (GED) and quantum chemical
calculations (B3LYP and MP2 in combination with cc-pVDZ and aug-cc-pVDZ basis sets).
For each compound the calculations predict the existence of two conformers which are
enantiomers. On the basis of the experimental data it was found that the gas phase over
b-NaphSF and b-NaphSCl at 357(5) K and 395(5) K, respectively, consists of molecular
species of C1 symmetry in which the Cb-S-Hal plane deviates from the perpendicular
orientation relative to the naphthalene skeleton plane. The following geometrica
parameters (Å and degrees) were obtained from the experiment (uncertainties are in
parentheses): rh1(C-H) = 1.097(7), rh1(C-C)av. = 1.410(3), rh1(C-S) = 1.753(6), rh1(S-
O)av. = 1.414(4), rh1(S-F) = 1.559(5), ÐC-Cb-C = 122.8(3), ÐCb-S-F = 103.3(30); Ca-Cb-
S-F = 104(6) for b-NaphSF, and rh1(C-H) = 1.089(4), rh1(C-C)aver. = 1.411(3), rh1(C-S) =
1.757(5), rh1(S-O)aver.= 1.419(3), rh1(S-_l) = 2.053(4), ÐC-Cb-C = 122.8(1), ÐCb-S-Cl =
102.2(7), Ca- Cb-S-Cl =108(3) for b-NaphSCl. The calculated barriers to internal rotation
of the sulphonyl halide groups exceed considerably the thermal energy values
corresponding to the temperatures of the GED experiments. Natural bond orbital (NBO)
analyses of the electron density distribution were applied to explain the peculiarities of the
molecular structure of the studied compounds and the deviation from the structures of their
benzene analogs.
We thank the Deutsche Forschungsgemeinschaft and Russian Fond of Basic
Researches for financial support of the Russian-German Cooperation (grants DFG OB
28/22-1 and RFBR 12-03-91333- HHИO-a)
Poster session
53
The electronic and geometric structure of the benzenesulfonic acid
methyl ester and its 2- and 4-nitro-substituted molecules
Nina I. Girichevaa, Mikhail S. Fedorova, Sergey N. Ivanova, Georgiy V. Girichevb
a Ivanovo State University, Russia
b Ivanovo State University of Chemistry and Technology, Russia The study of gaseous 2- and 4-nitrobenzenesulfonic acid methyl esters (2- NBSAME, 4-
NBSAME) was carried out by gas-phase electron diffraction and mass spectrometric
(GED/MS) experiment (T=380(5) _ and T=376(5) K correspondingly). The recorded mass
spectra indicated that compounds vaporize without decomposition at the temperatures of
the GED/MS experiments, and the saturated vapour consists of monomers. Theoretical
calculations (B3LYP/cc-pVTZ, MP2/cc-pVTZ) showed that the molecule 4- NBSAME has
three conformers: one of them possesses Cs symmetry (II) and two mirror conformers of
C1 symmetry (I and I*). The conformational compo-
sition of the studied vapor (I : II : I* equals 16 : 68 :
16 mol%), and the structure of the conformers were
determined by the GED method for the first time. The
molecule 2-NBSAME has six conformers with relative
energies 0, 1.08, 0.89, 1.77, 2.22 and 2.91 kcal/mol
(B3LYP/cc-pVTZ). Four conformers were taken into
account at LS-analysis of GED data. NBO analysis of
electronic structure of the 4-NBSAME and
2-NBSAME conformers was performed and the explanation of stability for the certain
geometric configurations was proposed. The stabilization of near
orthogonal position of single S–O(CH3) bond relative to benzene ring is due to essential
donor-acceptor interaction between bonding π(C-C) orbital of benzene ring and
antibonding σ*(S-O(CH3)) orbital of SO3 group. The stabilization of asymmetric position of
O–C bond is substantially related to anomeric effect between lone pairs LP1(sp0.79) and
LP2(p) of oxygen atom O(CH3) and antibonding orbitals σ*(C-S) and σ* S=O).
Poster session
54
Substituent effect on the geometric and electronic structure of
benzenesulfonic acid
Nina I. Giricheva a, Mikhail S. Fedorov a, Sergey N. Ivanov a, Georgiy V. Girichev b
a Ivanovo State University, Russia
b Ivanovo State University of Chemistry and Technology, Russia A combined gas-phase electron diffraction/mass-spectrometric and quantum chemical
(B3LYP/ccpVTZ, MP2/cc-pVTZ) study of the molecular structures of paramethyl-
benzenesulfonic acid (4-MBSA) and meta-nitrobenzenesulfonic acid (3-NBSA) was carried
out. On the basis of mass spectrometric analysis, it was found that the substituted
benzenesulfonic acids are thermostable at least up to 431(3) K. The fragmentations of 4-
MBSA and 3-NBSA molecules under electron impact were analyzed. Quantum chemical
calculations show that the 4-MBSA molecule exists as an enantiomeric pair, which is
formed as a result of rotation of OH group about the S–O(H) bond. The 3-NBSA molecule
has two conformers with different orientations of the O–H bond with respect to the nitro
group and two corresponding enantiomers. The equilibrium configurations of 4-MBSA and
both conformers of 3-NBSA have similar structures of the SO3H group, with the O–H bond
eclipsing one of the S=O bonds. Selected experimental bond distances for 4-MBSA/3-
NBSA are (A°) rh1(C–C)av = 1.403(3)/1.395(4); rh1(C–S) = 1.765(5)/1.784(5); rh1(S=O)av
=1.433(4)/1.438(4); and rh1(S–O) = 1.618(4)/1.620(4). The potential functions for the
internal rotation of SO3H, OH, and CH3 or NO2 groups were calculated, and the transition
states between enantiomers (conformers) were determined. The influence of substituent’s
nature on molecular geometry as well as on the energies of frontier orbitals and red-ox
properties of the compounds is discussed. The inductive and mesomeric substituent
effects were estimated from the donor–acceptor interaction energies of the natural bond
orbitals of substituent and benzene frame. The correlation between group electro-
negativities and cooperative energetic characteristics of inductive and mesomeric effects
of substituents is shown.
Poster session
55
Analysis of electron diffraction data for 1,3,5-trinitrobenzene molecule
with consideration of equivalence of large amplitude motion
coordinates
Kochikov I.V., Khaikin L.S.,Tikhonov D.S., Grikina O.E.
M.V. Lomonosov Moscow State University,
Research Computer Center and Department of Chemistry
For the first time, on the basis of joint consideration of the results of electron
diffraction experiment, quantum chemical calculation at the MP2(full)/cc-pVTZ level and
vibrational spectra, a planar equilibrium conformation with D3h symmetry has been reliably
established for nonrigid 1,3,5-trinitrobenzene molecule, which is characterized by three
equivalent internal rotation coordinates of NO2 groups (, and angles correspond to the
turns of each of the nitro groups relative to the planar conformation). Total number of
configurations in case of a grid of angle values with 30° step is 123 = 1728. Since the
abovementioned coordinates transform into each other upon rotation around the C3 axis,
this number decreases to 32 forms that are not reducible to each other (see the Table).
Among them, only 14 configurations account for 99% of the distribution density at the
experimental temperature of 455К.
No. , , (°) Sym. Stat. Weight
ΔE kcal/mol
No. , , (°) Sym. Stat. Weight
ΔE kcal/mol
1 0,0,0 D3h 8 0.0 (ES) 17 90,0,0 C2v 24 4.11
2 90,90,90 D3h 8 13.46 18 0,90,90 C2v 24 8.59
3 30,30,30 D3 16 2.36 19 30,0,0 C2 48 0.84
4 60,60,60 D3 16 9.22 20 60,0,0 C2 48 2.93
5 0,30,150 Cs 48 1.76 21 0,30,30 C2 48 1.63
6 0,60,120 Cs 48 6.14 22 0,60,60 C2 48 6.00
7 30,90,150 Cs 48 6.05 23 30,30,60 C2 48 4.55
8 60,90,120 Cs 48 10.84 24 30,30,90 C2 48 5.92
9 0,30,60 C1 96 3.76 25 30,30,120 C2 48 4.88
10 0,30,90 C1 96 5.04 26 30,30,150 C2 48 2.68
11 0,30,120 C1 96 3.93 27 30,60,60 C2 48 6.83
12 0,60,90 C1 96 7.33 28 30,90,90 C2 48 9.62
13 30,60,90 C1 96 8.25 29 30,120,120 C2 48 7.16
14 30,60,120 C1 96 7.10 30 60,60,90 C2 48 10.70
15 30,60,150 C1 96 4.82 31 60,60,120 C2 48 9.56
16 30,90,120 C1 96 8.34 32 60,90,90 C2 48 12.11
This work was supported by the Russian Foundation for Basic Research, projects No. 11_03_00716_a and No. 12_03_91330_NNIO_a. The authors are thankful to the member of Hungarian Academy of Sciences, Prof. I. Hargittai, for the opportunity to use the high-quality recordings of scattering intensities for 1,3,5-trinitrobenzene, which were obtained under his guidance at the Budapest University of Technology and Economics.
Poster session
56
Gas-phase electron diffraction and quantum chemical investigation of
the molecular structure of benzamide
Inna N. Kolesnikovaa, Olga V. Dorofeevaa, Igor F. Shishkova, István Hargittaib a Department of Chemistry, M.V. Lomonosov Moscow State University, 11999, Moscow,
Russia b Hungarian Academy of Sciences and Department of Inorganic and Analytical Chemistry,
Budapest University of Technology and Economics, PO Box 91, H-1521, Hungary
The molecular structure of benzamide was determined by gas-phase electron diffraction (GED) and quantum chemical calculations (B3LYP and MP2 methods, cc-pVTZ basis set). The differences between a few selected geometrical parameters were constrained at values calculated at the MP2/cc-pVTZ level of theory. Consequences of steric effect of
the amino group were observed in r(C–C(C=O)), C2C1C7 and C2C1C7O8. The C=O bond is 0.02 Å shorter than that in the crystal and the C–N bond is 0.05 Å longer than that in the crystal. These differences are close to the corresponding differences found for formamide and acetamide.
Parameter a B3LYP/cc-pVTZ MP2/cc-pVTZ GED
C1–C7 1.501 1.487 1.509(4)
(C C)av 1.391 1.405 1.398(1)
C=O 1.218 1.219 1.223(3)
C–N 1.370 1.364 1.386(1)
(C–H)av 1.082 1.076 1.386(4)
(N–H)av 1.105 1.103 1.107(3)
C–C=O 122.0 122.1 121.6(16)
C–C=N 116.3 115.6 116.6(15)
C2–C1–C7 117.6 117.4 117.4(1)
(C C C)av 120.1 120.1 120.0(1)
(C C–H)av 120.1 120.2 120.2b
C7–N–H10 116.0 115.5 115.5b
C7–N–H11 120.8 119.6 119.6b
C2–C1–C7=O 19.1 19.9 19.5(107)
C1–C7–N–H10 -161.9 -161.3 -161.5(87)
Rf,% 2.4
aBond lengths are in Å and bond angles are in degrees; bAssumed at the value from MP2/cc-pVTZ calculations.
This research was supported by the Russian Foundation for Basic Research under the Grants No. 11-03-00716-a and No. 12-03-91330-NNIO_a.
Poster session
57
Molecular structure and conformation of 1,3,5-tris(trifluoromethyl)-
benzene as studied by gas-phase electron diffraction and quantum
chemical calculations
Inna N. Kolesnikovaa, Olga V. Dorofeevaa, Igor F. Shishkova, Rykov A. N.a, Karasev N. M.a, Heinz Oberhammerb
aDepartment of Chemistry, M.V. Lomonosov Moscow State University, 11999, Moscow,
Russia bInstitut für Physikalische und Theoretische Chemie, Universität Tübingen, 72076
Tübingen, Germany
The molecular structure of 1,3,5-tris(trifluoromethyl)benzene (1,3,5-TTFB) has been studied by gas-phase electron diffraction (GED) and quantum chemical calculations (B3LYP method with 6-31G(d,p), cc-pVTZ basis sets, and MP2 method with cc-pVTZ
basis set). The differences between geometrical parameters were constrained at values calculated at 6-31G(d,p) level. Quantum chemical calculations predict nearly free rotation of the three CF3 groups around Cphenyl-Cmethyl bonds. The GED intensities of 1,3,5-TFB can be fitted almost equally well with a single conformer with C1 symmetry (Rf = 4.2%), or with a mixture of 39(10)% C3h, 37(10)% Cs, and 24(10)% C3v
conformers (Rf = 4.4%). The GED results are in a good agreement with ab initio calculations.
Molecular structure of 1,3,5-TFB obtained by gas-phase electron diffraction and quantum chemical calculations
a Bond lengths are in Å and bond angles are in degrees; α=C2–C1–C7–F12, β=C4–
C3–C8–F15, γ C6–C5–C9–F18
This research was supported by the Russian Foundation for Basic Research under the Grants No. 11-03-00716-a and No. 12-03-91330-NNIO_a
Para-meter a
B3LYP/6-31G(d,p) GED
1 conf.
mixture 1 conf.
mixture
C3h Cs C3v C3h Cs C3v
(C–F)av 1.347 1.345 1.347 1.347 1.347(2) 1.346(2) 1.348(2) 1.347(2)
(C C)av 1.389 1.391 1.389 1.389 1.388(5) 1.392(5) 1.392(5) 1.392(5)
(C–C)av 1.509 1.508 1.509 1.509 1.511(5) 1.510(5) 1.508(5) 1.511(5)
α 33.0 59.5 29.1 29.6 19.9(10) 60.7(16) 29.7(24) 29.0
β 75.8 59.5 30.8 -29.6 56.2(10) 60.7(16) 31.4 -29.0
γ 75.9 59.5 -151.5 -29.6 77.1(10) 60.7(16) -152.4 -29.0
P,% 100 29 37 34 100 39(10) 37(10) 24(10)
Rf,% 4.2 4.4
C6
C5C4
C3
C2
C1
C7
C8C9
F10
F11F12
F13
F14F15
H19H21
H20
F18
F17F16
Poster session
58
Large-amplitude motions for methyl trifluoroacetate and 2, 5-
dimethylfuran by GED, MW and quantum chemical calculation
Nobuhiko Kuzea, Atsushi Ishikawaa, Yuya Onoa, Hiroshi Takeuchib and Shigehiro Konakab
aSophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan
E-mail: [email protected]
bDepartment of Chemistry, Faculty of Science, Hokkaido University, Sapporo
060-0810, Japanw
Gas electron diffraction (GED) and the vibrational study of methyl trifluoroacetate
(CF3COOCH3) were reported in 20091. The precise molecular structure of this compound
was determined by the University of Edinburgh in this paper. We have carried out the GED
of methyl trifluoroacetate at Hokkaido University independently. We found that our GED
data was reproduced well if we considered the large-amplitude motion of the CF3 group. In
this work, we will present the dynamical model of this compound by analysing the GED
data and rotational constant. Jones et al. have been observed the microwave (MW)
spectrum and determined the rotational constants of this molecule2. We have observed
and assigned some additional absorption lines for our MW spectrum, the results were
used for the combined analysis of GED and MW data.
Another example for the dynamic model analysis of GED data is 2, 5-dimethylfuran which
is known as the candidate for the biofuel. We are trying to determine the potential
parameters of the internal rotations for the two methyl groups. Details of the data analysis
as well as the LCNMR data analysis will be presented.
1 M. E. D. Lestard, M. E. Tuttolomondo, E. L. Varetti, D. A. Wann, H. E. Robertson, D. W.
H. Rankin and A. B. Altabefa, J. Raman Spectrosc., 2009, 40, 2053.
2 G. I. L. Jones, T. D. Summers and N. L. Owen,J. Chem. Soc., Faraday Trans., 1973,
70, 100.
Poster session
59
Molecular structure study of some methyl derivatives of uracil
by electron diffraction method and high-level ab initio calculations
Ilya I. Marochkin a, Natalja Vogt b, Anatolii N. Rykov a, Olga V. Dorofeeva a, Jürgen Vogt b,
and Igor F. Shishkov a
a Moscow State University, Chemistry Department, Moscow, Russia;
b University of Ulm, Chemical Information Systems, Ulm, Germany
The determination of the molecular structure of 1-methyluracil and 1-methylthymine has
been carried out by gas-phase electron diffraction (GED) method and high-level ab initio
calculations (up to CCSD(T)). According to results of the MP2/cc-pVTZ calculations, both
molecules exist as a single conformer with a planar skeleton and a methyl group at the N
atom in a staggered position with respect to the N-C(=O) bond (the second methyl group
in 1-methylthymine has also staggered conformation relative the C-C(=O) bond) as shown
in Fig. 1 (Cs total symmetry). In the GED analysis for each molecule, the differences
between the N-C bond lengths and between the C-C bond lengths are fixed at the values
of the calculated “best ab initio” structure, and the large-amplitude motion of the CH3 group
at the N atom is described by a dynamic model yielding essentially lower R factor than a
static one. The equilibrium structure has been determined from experimental data taking
into account harmonic and anharmonic vibrational corrections calculated from
MP2/cc-pVTZ quadratic and cubic force fields, respectively.
The equilibrium structural parameters of 1-methyluracil and 1-methylthymine obtained from
GED data are found to be very close to those of the “best ab initio” structure.
This work was supported by the Russian Foundation for Basis Research Grant
№ 11-03-00716-а and 12-03-91330-NNIO-а and by the German Barbara Mez-Starck
Foundation.
Fig. 1. The molecular structure of 1-methylthymine (left) and 1-methyluracil (right)
Poster session
60
Electron-nucleus overlap & parity-violating effects in PbF, YbF, and RbF
Zachary Glassman1, Benjamin Girodias1, Richard Mawhorter1,
Timothy Steimle2, Michaela Jahn3, and Jens-Uwe Grabow3
1Physics Dept., Pomona College, Claremont, CA 91711 USA
2Chemistry Dept., Arizona State University, Tempe, AZ 85287 USA
3Institut für Physikalische Chemie, Leibniz-Universität, Hannover D 30167
The shape or electric dipole moment of the
electron (eEDM) is a fascinating mystery which could
prove to unlock a path to physics beyond the standard
model. While the standard model predicts that the eEDM
is less than 10-40 e·cm, the majority of other theories and
models predict the eEDM to be much larger. The current
limiting measurement is on the order of 10-27 e·cm, made
by a team from Imperial College on the open shell
molecule YbF. Current experiments are focusing on this
and other heavy free radicals, which in weak external polarizing fields can exhibit very
large internal effective electric fields (~10 - 100 GV/cm) near the nucleus of the larger
atom. Observing the nuclear electric hyperfine structure (eQq) for YbF will help constrain
the wave functions used to calculate these huge internal fields. There is also a very small
but nonzero probability that the unpaired electron will be near and even inside the nucleus,
resulting in a slight perturbation to the nuclear quadrupole moment for closed shell
molecules like RbF as well as in shifts due to parity-violating (PV) effects due to the
relativistic electron-nucleus interaction in molecules like YbF and PbF. These include the
larger spin-dependent anapole moment as well as the tiny spin-independent eEDM. We
use Fourier transform microwave spectroscopy with sub-kilohertz resolution to explore the
sensitivity of these molecules to these subtle but fascinating effects, which is motivated in
the figure by Neil Shafer-Ray showing the handedness of molecular rotation in an orienting
external field.
Poster session
61
The structure of free copper (II) 2,9,16,23-tetra-tert-butyl-
phthalocyanine: preliminary DFT calculations
Oleg A. Pimenov, Georgiy V. Girichev and Vladimir E. Maizlish
Ivanovo State University of Chemistry and Technology, 153 000 Ivanovo, Engels av. 7,
Russia
The DFT calculations of copper (II) 2,9,16,23-tetra-tert-butyl-phthalocyanine (CuTTBPc)
molecule were performed. Two
different approaches (UB3LYP and
ROB3LYP) were employed with 6-
31G* basis set, and two force fields
were used to make the starting
molecular model in gas electron
diffraction (GED) refinement. The
calculations UB3LYP/cc-pVTZ (N, C,
H) with Stuttgart relativistic
pseudopotential for Cu are carried
out also.
The DFT optimized geometry of CuTTBPc has the symmetry C4h (Fig). In the
equilibrium configuration the C-C bond of the tert-butyl group eclipses the C-C bond of the
benzene ring in macrocycle. The computations predict the internal rotation of the tert-butyl
groups to be independent. The barrier of internal rotation is 3.3 kJ/mol (UB3LYP/6-31G*)
for single tert-butyl group. The distance between neighbouring tert-butyl groups is about 9
Å. The thermal energy of CuTTBPc for the temperature of GED experiment (T=744 K) RT=
6.2 kJ/mol, and tert-butyl groups rotation is practically free at this conditions.
The geometries of CuTTBPc molecule from restricted and unrestricted approaches
are identical. The structural parameters of macrocycle frame of CuPc are close to
geometry of macrocycle frame in CuTTBPc. Thus, the tert-butyl substituents have weak
influence on the phthalocyanine macrocycle structure.
Authors thank the Russian Foundation for Basic Research, RFBR (Grant 13-03-
00975a) for financial support.
Poster session
62
The molecular structure of zinc(II) etioporphyrin-II:
a gas-phase electron diffraction and quantum chemical study
Alexander Pogonin a, Natalya Tverdova a, Anatoly Ischenko b and Georgiy Girichev a
a Ivanovo State University of Chemistry and Technology, Research Institute of Chemistry
of Macroheterocyclic Compounds, F. Engels av. 7, Ivanovo, 153000, Russian Federation
b Moscow Lomonosov State University of Fine Chemical Technologies, Vernadskogo 86,
Moscow 119517, Russian Federation
Gas-phase molecular structure of zinc(II) etioporphyrin-II (ZnEP-II) has been studied by
a synchronous gas-phase
electron diffraction and mass
spectrometry method and DFT
calculations using the B3LYP and
PBE functionals with pVTZ basis
sets for describing H, C, N atoms
and cc-pVTZ for describing Zn
atom.
The mass spectrum consists of
two groups of peaks corres-
ponded to single and double charged parent ion and ions formed by consecutive
removal of hydrocarbon groups (-СH3, –С2H5, –С2H4) by an electron impact.
The molecule ZnEP-II was found to possess quasiplanar geometry of macro-
heterocycle. Five conformers of this compound have been studied by DFT computations.
Energetic differences of these conformers are less than 0.1 kJ/mol. Rotation barriers of
ethyl group are 15.7 and 20.6 kJ/mol (B3LYP). Every bonded internuclear distances in
different conformers are practically the same, and it is impossible to distinguish сonformers
from each other using GED-method.
Structural parameters of the ZnEP-II molecule yielded by the GED are generally in good
agreement with DFT calculations and X-ray data on crystalline zinc(II) octaethylporphyrin
(ZnOEP).
Authors thank the Russian Foundation for Basic Research, RFBR (Grant 13-03-00975a)
for financial support.
Poster session
63
Ab initio calculations of DNA nucleobases and simulation of electron
diffraction patterns
K. Siddiqui1,2, G. Corthey1, T. Hasegawa1, S. Hayes1, K. Pichugin1, G. Sciaini1, R.J.D.Miller1 and B. J.Whitaker2
1Max Planck Research Department for Structural Dynamics, Center for Free electron
Laser Science, University of Hamburg. Luruper Chaussee 149, 22761, Hamburg,
Germany.
2School of Chemistry, Unviersity of Leeds, Leeds LS2 9JT, UK.
Deoxyribonucleic acid (DNA) bases, i.e., adenine, thymine, cytosine and guanine are the
building blocks of life. They exhibit interesting photophysics in the ultra-violet/visible range
in that, after excitation, they are rapidly deactivated (τdeactivation ~ 100 fs – 1 ps). This
ultrafast deactivation is proposed to be the reason behind DNA’s remarkable photostability
and evolution of life on Earth [1]. Ultrafast Electron Diffraction (UED) is a technique ideally
suited to studying such processes with both atomic spatial and femtosecond time
resolution [2]. We are interested in trying to identify key states of DNA bases that play a
part in the deactivation and hence elucidate the mechanism of DNA photostability using a
combination of Ab inito calculations at the complete active space self-consistent field
(CASSCF) level and UED. In this poster, we present some results from Ab initio
calculations done on adenine and thymine. The structures obtained from these
calculations are used to simulate electron diffraction patterns as an experimental feasibility
study.
1 Hernadez et al ,Chem. Rev. 2004, 104,1977–2019.
2 G.Sciani and R.J.D Miller, Rep. Prog. Phys. 2011, 74, 96101.
Poster session
64
Molecular structure of thulium tris-dipivaloylmethanate, Tm(thd)3, by
gas electron diffraction (GED) and DFT calculations.
Natalya V. Belova, Valery V.Sliznev, Georgiy V.Girichev, Oleg A. Pimenov
Research Institute for Thermodynamics and Kinetics of Chemical Processes,
Ivanovo State University of Chemistry and Technology, Russia
Geometrical and electronic structure,
intramolecular rearrangements and the internal
rotation of thulium tris-dipivaloylmethanate,
Tm(thd)3, were studied by gas phase electron
diffraction and quantum chemical calculations.
Theoretical calculations were performed using
DFT method (B3LYP, PBE0) and cc-pVTZ basis
sets. Core shells of Tm including partially
occupied 4f-shell were described by Stuttgart
relativistic pseudopotential. NBO-analysis was applied to description of chemical bonding.
The calculations show that the complex, Tm(thd)3, possess the equilibrium
configuration of D3 symmetry (fig.). The relative energy of D3h structure corresponding to
the barrier on the path of the intramolecular rearrangement is 7.4 (B3LYP) or 4.7 kJ/mol
(PBE0). In the equilibrium configuration the C-C bond of the tert-butyl group eclipses the
C-C bond of the chelate ring. The structure with eclipsed C-O bond corresponds also to
the local minimum on PES. Relative energies of these configurations are 3.4 for single tert-
butyl group and 22.3 kJ/mol for all tert-butyl groups.
The interpretation of ED data was performed only for D3 configuration. Quantum
chemical structure is close to experimental rh1 parameters. Obtained geometrical
parameters of Tm(thd)3 molecule were compared with available data for similar
compounds.
Poster session
65
Molecular structure of L-tryptophan
Valeriya V. Tyunina, Nina I. Giricheva*, and Georgiy V. Girichev
Ivanovo State University of Chemistry and Technology, 153000 Ivanovo, Engels av. 7,
Russia
* Ivanovo State University, 153025 Ivanovo, Ermak st. 39, Russia
Amino acids are model compounds of proteins taking part in many important biochemical
processes such as neuroregulation, enzyme catalysis, etc. These substances are well-
known to exist as zwitterions in the solid state and aqueous solution, amino acids,
however, having a molecular form in the gas phase. Besides, amino acid molecule has a
low symmetry and many rotational degrees of freedom. Therefore, molecules have a large
number of different low energy conformers on the potential energy surface. In this work
investigation of saturated vapour of L-tryptophan was carried out by gas electron
diffraction and mass spectrometry at T=495 K. Mass spectra have a typical fragmentation
for amino acids: elimination of side chain and carboxylic group and registration of ions:
COOH+, NH2CHCO+, NH2CH+. The major peaks were observed at m/z = 130 (C9H8N+) and
m/z = 204 (molecular form). Enthalpy of sublimation was found by thermodynamics law II:
sH(Trp)=184(3) kJ/mol at T=450 K. The geometries, energies and vibrational frequencies
of tryptophan conformers were calculated using B3LYP/cc-pVTZ level of theory.
Conformers have different orientations of carboxylic and amine group, backbone and
indole fragment to each other. The most stable conformers of tryptophan have
intramolecular hydrogen bond between carboxylic and amide group. It should be noted
that 8 conformers should be used at LS refinement of GED data. These conformers can be
divided at two groups: distinguishable [with different torsion angle C(OOH)-C(HNH2)-
C(H2)-C(ind)] and indistinguishable [with different torsion angles H-N-C-C and H-O-C-C] by
GED. It is shown the capabilities and limitations of GED method at determination the
structure of molecules with large number of conformers.
This study was supported by Russian Foundation for Basis Research (project № 12-03-
31758mol_а).
Poster session
66
Modernization of electron diffractometer EMR-100M
Nikolai M. Karasev a, Maxim A. Abaev a, Alexander M. Makurenkov a, Natalja Vogt b,
Werner Leikam c, Jürgen Vogt b, and Igor F. Shishkov a
a Moscow State University, Chemistry Department, 119991 Moscow, Russia;
b University of Ulm, 89069 Ulm, Germany;
c Staib Instruments, 85416 Langenbach, Germany
After introducing the imaging plate registration system1, the experimental equipment in the
electron diffraction (ED) laboratory of the Moscow State University has been further
modernized. The electron diffractometer EМR-100М, originally produced in Sumy
(Ukraine) the solid state electron diffraction in 1981, has been equipped with the custom-
made electron gun system GDS60, a new evaporator (similar to that constructed for EG-
100 diffractometer by A. A. Ivanov) with a medium-temperature nozzle and two separate
inlet valves for the gas standard and the sample, as well as a new sector construction.
Moreover, the turbo molecular pump system (with HiPace80 pump), which allows to reach
the vacuum during experiment up to 10-7 mbar, has been
installed. The functionality of the modernized electron
diffraction system has been proven on the test object
CCl4. Its advantages will be discussed.
This work has been carried out in the cooperation
between the Electron Diffraction laboratory of Moscow
State University and the section Chemical Information
Systems and has been supported by the Russian
Foundation for Basis Research (Grants № 11-03-00716-а
and 12-03-91330-NNIO-а) and by the German Barbara
Mez-Starck Foundation.
Fig.: Photograph of the modernized gas electron diffractometer EМR-100М at the Moscow
State University.
1 N. Vogt, R. Rudert, A. N. Rykov, N. M. Karasev, I. F. Shishkov, and J. Vogt: Struct.
Chem., 2011, 22, 287.
Poster session
67
Comparative analysis of structures of succinimide and its N-derivatives
in crystalline and gaseous phases
L.A. Zasurskaya, A. E. Obodovskaya
Chemistry Department of M.V. Lomonosov Moscow State University, Moscow, Russia
A comparison of molecular structures of succinimide (Su) and its N-derivatives
(CH2CO)2NX in gaseous phase (X = CH3, Cl, Br) and in crystals (X = H, OH, Cl, Br, I, CH3
and NO2) was performed using GED1 and X-ray (CSD)2 experimental data.
In all molecules, both in gaseous and crystalline phases, the lengths of N–X bonds are
nearly equal. For all molecules GED shows that the heterocycle is planar (СССС = 0),
while in crystals it is almost planar only in Su (СССС = 2.7). The values of СССС are
slightly larger in its N-derivatives: 5.8 (OH), 8.1 (Cl), 4.0 (Br), 7.1 (I), 11.1 (CH3)
and 10.5 (NO2), which indicates the flexibility of the cycle. The analysis of molecular
packing in the Su crystal shows that centrosymmetrical dimers of molecules linked by H-
bonds of the NH٠٠٠O type are formed in the structure. The dimers are united into "parquet"
layers by 4 short C٠٠٠O contacts (О٠٠٠centroid distance is 2.880 ), while the stacking of
the layers produces the crystal (Pbca, Z = 8). NO2–Su crystallizes in the same space
group. In this case, however, the structure is formed by chains and layers united by
CH٠٠٠O bonds. The structures with X = OH, Cl and Br (P212121, Z = 4) are made of
ribbons, in which molecules are related by axis 21. In ОН-Su ribbons are formed by strong
intermolecular О-Н٠٠٠О bonds, C-H٠٠٠O bonds and short С٠٠٠О contacts (like in Su). In
isostructural Cl-Su and Br-Su the molecules in the ribbons are united not only by C-H٠٠٠O
bonds, but also by short Hal٠٠٠O and Hal٠٠٠Hal contacts. The tetragonal structure of I–Su
(P41, Z = 4) is rare for molecular crystals. Short contacts I٠٠٠О make molecules related by
axis 41 form helices united by C-H٠٠٠O bonds. In monoclinic structure СН3-Su (P21/n, Z=4)
molecules related by axis 21(Y) form ribbons due to CMe–H٠٠٠O interactions and layers due
to CH٠٠٠O bonds.
1 Yu. V. Vishnevskiy, L. V. Vilkov, A. A. Ivanov, V. V. Kuznetsov, N. N. Makhova, N. Vogt,
J. Vogt, IV-th National Crystal Chemistry Conference, Chernogolovka (Russia), 2006, 322.
2 F. H. Allen, Acta Crystallogr. B. 2002, 58, 380.
Poster session
68
The structure of a thiadiazole-containing expanded
heteroazaporphyrinoid determined by gas-phase electron diffraction
and DFT calculations
Yuriy Zhabanov, Alexander Zakharov, Sergei Shlykov, Mikhail Islyaikin, and Georgiy
Girichev
Ivanovo State University of Chemistry and Technology, Research Institute of Chemistry of
Macroheterocyclic Compounds, F. Engels av. 7, Ivanovo, 153000, Russian Federation
Macroheterocyclic compounds of ABABAB type containing 1,3,4-thiadiazole rings are a
relatively new class of expanded porphirinoids.1, 2 In 2008 we reported3 the first direct
characterization of the molecular structure of the tert-butyl-substituted macrocycle
(C42H39N15S3) by a synchronous gas electron diffraction and mass spectrometric
experiment and DFT calculations. In this study we have investigated the unsubstituted
(C30H15N15S3, see the figure) compound by a synchronous gas electron diffraction and
mass spectrometric experiment and density functional theory calculations using the B3LYP
and M06 hybrid functionals and cc-pVTZ basis sets. The six tautomers of this compound
have been studied by DFT computations. The molecule
has an equilibrium structure of D3h symmetry with a
planar macrocycle and the thiadiazole rings oriented in
such a way that the sulfur atoms point outwards from
the inner cavity. The existence of hydrogen bonds was
confirmed by NBO analysis. According to the NBO
analysis there is an interaction between lone pairs of N
atoms in thiadiazole rings and anti-bonding N-H
orbitals.
This work was supported by a grant RFBR 13-03-00975
1 M. K. Islyaikin, E. A. Danilova, L. D. Yagodarova, M. S. Rodríguez-Morgade, T. Torres,
Org. Lett. 2001, 3, 2153.
2 N. Kobayashi, S. Inagaki, V. N. Nemykin, T. Nonomura, Angew. Chem., Int. Ed. 2001,
40, 2710.
3 A. V. Zakharov, S. A. Shlykov, S. A. Bumbina, E. A. Danilova, A. V. Krasnov, M. K.
Islyaikin, G. V. Girichev, Chem. Commun., 2008, 3573.
Poster session
69
REGAE: Towards Ultrafast electron diffraction and dynamic microscopy Dongfang Zhang,1 Stephanie Manz,1 Albert Casandruc,1 Julian Hirscht,1 Sercan Keskin,1
Jeff Nicholls,4 Kostyantyn Pichugin,1 Stuart Hayes,1 Santosh Jangam,1 Taisuke
Hasegawa,1 Alexander Marx,1 Shima Bayesteh,2 Hossein Delsim-Hashemi,2 Matthias
Felber,2 Holger Schlarb,2 Matthias Hoffmann,2 Markus Huening,2 Tim Gehrke,3 Frank
Mayet,3 Max Hachmann,3 Gustavo Moriena,4 Sascha Epp,1 Masaki Hada,1 Klaus
Floettmann,2 R. J. Dwayne Miller,1,4
1Max Planck Research Department for Structral Dynamics, Center for Free Electron Laser
Science, University of Hamburg, Luruper Chausee 149, 22761 Hamburg, Germany
2Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607, Hamburg, Germany
3Institute for Experimental Physics, Center for Free Electron Laser Science, University of
Hamburg,, Luruper Chaussee 149, 22761 Hamburg, Germany
4Department of Chemistry and Physics, University of Toronto, 80 St. George st., Toronto,
Ontario M5S3H6, Canada
The Relativistic Electron Gun for Atomic Exploration (REGAE) has been designed to study
structural dynamics in solid, solution and gas phase on the femtosecond timescale.
REGAE is based on rf-accelerated electron source generating 2–5 MeV electron bunches.
The electron energy, beam size, pulse duration and coherence length in REGAE were
theoretically characterized with a space charge tracking algorism (ASTRA) 1. Exploiting
arebunching rf cavity, the electron pulses from REGAE are expected to be as short as 7 fs
(rms) with high electron density (106 electron/pulse), small transverse emittance (6×10−3
mm mrad) and long coherence length (~30 nm). The excellent temporal and spatial
resolution of this relativistic electron source will open up a new frontier for ultrafast electron
diffraction and dynamic microscopy.
1 K. Flöttmann, Astra, http://tesla.desy.de/~meykopff/.