BOOK OF ABSTRACTS

FIRST INTERNATIONAL MEETING

ON RECENT DEVELOPMENTS IN

THE STUDY OF RADIATION

EFFECTS IN MATTER.

5th - 8th December, 2006

PLAYA DEL CARMEN QUINTANA ROO, MEXICO.

In recent years we have seen a rapidly increasing research activity towards the development

and understanding of novel synthetic materials with particular emphasis on their properties at

the nano-metric level. The quest for synthesis, analysis and modification of modern materials

has come from a variety of approaches amongst which are very promising perspectives using

radiation- laser, gammas, electrons, ions

The rapid pace at which international research is driving towards new classes of materials

makes it timely to establish forums of discussion to review both the state -of- the art and

future directions of radiation.

The Meeting will be held in the quiet and picturesque region of Playa del Carmen, Q. Roo,

on the Mexican Caribbean during December 5th – 8th, 2006, being the first of a series of

meetings aimed at gathering specialists in the field of radiation effects and related areas of

expertise. Our wish is that these inspiring surroundings will provide the framework for intense

scientific exchange in formal and informal discussions on recent advances in theoretical and

experimental aspects of the effects of radiation in matter.

A FESTSCHRIFT DEDICATED TO LEWIS T. CHADDERTON FOR HIS FIFTY YEARS IN

PHYSICS

The Organizing Committee also wishes this meeting to be a

Festschrift to recognize Lewis T. Chadderton of the Australian

National University, on the occasion of his 68th birthday and

his fifty years of scientific contributions in a wide number of

areas in physics - including those listed as topics at this

meeting. Lew Chadderton has been a decisive contributor to the knowledge inter alia of radiation effects and damage in

solids, crystal lattice defects, amorphous solids, fission

damage and fission tracks, electron channeling, geo- and

thermo-chronology, transmission electron microscopy and total

current spectroscopy.

His attitude towards new problems in physics has been always inspiring for many colleagues

and with a restless spirit he continues opening new arenas internationally in the area of

modern materials research. The breadth of topics in this meeting and their timely relevance

do indeed, in themselves, also provide laudable grounds for this special Festschrift

International Organizing Committee:

S. A. Cruz ( Physics Department, Universidad Autónoma Metropolitana, México)

L. C. Feldman (Dept. of Physics and Astronomy, Vanderbilt University, USA )

D. Fink ( Hahn-Meitner-Institut, Berlin, Germany)

A.P. Pathak (School of Physics, University of Hyderabad, India)

M. C. Ridgway (RSPhysSE, Australian National University, Australia)

Local Organizing Committee:

R. Cabrera-Trujillo (Centro de Ciencias Físicas, UNAM-Cuernavaca, México)

C. Cisneros (Centro de Ciencias Físicas, UNAM-Cuernavaca, México)

G. Espinosa ( Instituto de Física, UNAM, México)

E. Haro-Poniatowski ( Physics Department, Universidad Autónoma Metropolitana, México)

J. L. Hernández-Pozos (Physics Department, Universidad Autónoma Metropolitana, México)

A. I. Oliva (Centro de Investigacion y de Estudios Avanzados, IPN-Mérida, México) )

SPONSORS

The Organizing Committee wishes to thank the following institutions for their valuable support for

making this Meeting possible:

Universidad Autónoma Metropolitana

Universidad Nacional Autónoma de México Centro de Ciencias Físicas-Cuernavaca

Instituto de Ciencias Nucleares Instituto de Física

Instituto de Investigaciones en Materiales

Sociedad Mexicana de Física División de Física de Radiaciones

Centro de Investigación y de Estudios Avanzados, IPN Unidad Mérida

Secretaria de Educación Pública.

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FIRST INTERNATIONAL MEETING ON RECENT DEVELOPMENTS IN

THE STUDY OF RADIATION EFFECTS IN MATTER.

Playa del Carmen, Quintana Roo.

Dec 5th – 8th, 2006.

TUESDAY, DECEMBER 5TH, 2006.

8:30 – 9:00 WELCOME AND OPENING.

SESSION I.

CHAIRMAN: R. A. BARAGIOLA.

9:00-9:30 (TUE-01)

"SI IMPLANTATION IN SI, RADIATION DAMAGE AND POINT DEFECT

ENGINEERING"

WEI-KAN CHU UNIVERSITY OF HUSTON, USA

9:30-10:00 (TUE-02)

“VIBRATIONAL DYNAMICS AND BOND BREAKING OF H-SILICON”

LEONARD C FELDMAN VANDERBILT UNIVERSITY, USA

10:00-10:30 (TUE-03)

“ION BEAMS FOR NANO-SCALE SYNTHESIS”

DARYUSH ILA ALABAMA A & M UNIVERSITY, USA

---------- COFFEE ----------

SESSION II

CHAIRMAN: G. MARLETTA 10:45 -11:15

(TUE-04) “SCALING LAWS FOR GUIDING HIGHLY

CHARGED IONS THROUGH NANOCAPILLARIES IN INSULATING PET

POLYMERS”

NIKOLAUS STOLTERFOHT HAHN-MEITNER-INSTITUT BERLIN,

GERMANY

11:15 – 11 45 (TUE-05)

CREATION OF SUFACE NANOSTRUCTURES BY IRRADIATION WITH SLOW HIGLY

CHARGED IONS

FRIEDRICH AUMAYR TECHNICAL UNIVERSITY, WIEN,

AUSTRIA

11:45-12:15 (TUE-06)

SPATIAL AND ELECTRONIC CHARACTERIZATION OF NANO-FEATURES

CREATED BY HIGHLY CHARGED IONS

JOSHUA M POMEROY NATIONAL INSTITUTE OF STANDARDS

AND TECHNOLOGY GAITHERSBURG, USA

---------- COFFEE ----------

SESSION III

CHAIRMAN: J. AIZPURUA

12:30 – 13:00 (TUE-07)

SURFACE MODIFICATION OF PLOYMERS

GIOVANNI MARLETTA UNIVERSITA DEGLI STUDI DI CATANIA

ITALY

13:00 – 13:30 (TUE-08)

COLLECTIVE ELECTRONIC EXCITATIONS AT METAL SURFACES

VYACHESLAV M SILKIN DONOSTIA INTERNATIONAL PHYSICS

CENTRE, SAN SEBASTIAN, SPAIN

---------- LUNCH ----------

SESSION IV

CHAIRMAN: Z. L. MISKOVIC

16:15-16:45 (TUE-09)

NANOSCALE OPTICAL MICROSCOPY AND SPECTROSCOPY: NANOPARTICLE

PLASMONICS

JAVIER AIZPURUA DONOSTIA INTERNATIONAL PHYSICS

CENTRE, SAN SEBASTIAN, SPAIN

16:45 -17:15 (TUE-10)

IRRADIATION EFFECTS ON METAL NANOCRYSTALS

PATRICK KLUTH THE AUSTRALIAN NATIONAL

UNIVERSITY, CANBERRA, AUSTRALIA.

17:15 - 17:45 (TUE-11)

UV-LASER AND ELECTRON IRRADIATION EFFECTS ON SILVER NANOSTRUCTURES

E HARO-PONIATOWSKI UNIVERSIDAD AUTÓNOMA

METROPOLITANA, MEXICO CITY, MEXICO

19:30 HRS, RECEPTION COCKTAIL

WEDNESDAY, DECEMBER 6TH, 2006.

SESSION I

CHAIRMAN: A. DUNLOP

8:30-9:00 (WED-01)

SHINY QUARTZ: CATHODOLUMINESCENCE AFTER ION-IRRADIATION

KLAUS PETER LIEB UNIVERSITÄT GÖTTINGEN,

GERMANY

9:00-9:30 (WED-02)

EFFECT OF ION IRRADIATION AND POST-ANNEALING ATMOSPHERE ON THE

PHOTOLUMINESCENCE INDUCED BY SI NANOCRYSTALS PRODUCED BY HOT

IMPLANTATION IN SIO2

MONI BEHAR UNIVERSIDADE FEDERALE RIO GRANDE SUL, PORTO ALEGRE,

BRASIL

9:30-10:00 (WED-03)

STRUCTURAL CHARACTERISTICS OF NANOCRYSTALLINE ZRO2 POWDER SOL-

GEL DERIVED FOR LUMINESCENCE APPLICATIONS

TEODORO RIVERA INSTITUTO POLITÉCNICO NACIONAL,

MEXICO CITY, MEXICO

10:00-10:30 (WED-04)

DOSE RATES EFFECTS ON THE THERMOLUMINESCENT PROPERTIES OF

MWCVD DIAMOND FILM

MARCELINO BARBOZA-FLORES UNIVERSIDAD DE SONORA,

SONORA, MEXICO

---------- COFFEE ----------

SESSION II

CHAIRMAN: R. TENNE

10:45 -11:15

(WED-05) ION BEAM SYNTHESIS OF QUANTUM DOTS

IN INSULATORS HARRY BERNAS

UNIVERSITÉ PARIS SUD PARIS, FRANCE

11:15 – 11:45

(WED-06) NONLINEAR OPTICAL SUSCEPTIBILITIES IN

THIN METAL-DIELECTRIC MULTILAYERS GROWN BY PULSED LASER DEPOSITION

LUIS HERNANDEZ-POZOS UNIVERSIDAD AUTÓNOMA

METROPOLITANA, MEXICO CITY, MEXICO

11:45-12:15

(WED-07) COLOR CENTERS ENVISIONED AS

CONFINED QUANTUM SYSTEMS: THE CASE OF F, F´AND F2

+ CENTERS

JOSE LUIS MARIN UNIVERSIDAD DE SONORA,

SONORA, MEXICO

---------- COFFEE ----------

SESSION III

CHAIRMAN: F. AUMAYR

12:30 – 13:00 (WED-08)

CHIRIAL THIN FILMS: FABRICATION AND PROPERTIES

EVA SCHUBERT UNIVERSITY OF NEBRASKA-LINCOLN,

USA

13:00 – 13:30 (WED-09)

THERMALIZED NON-EQUILIBRATED MATTER: FROM MICROSCOPIC SYSTEMS

TO NANOSTRUCTURES

SERGEY Y KUN UAEM-CUERNAVACA, MEXICO &

AUSTRALIAN NATIONAL UNVERSITY, AUSTRALIA

---------- LUNCH ----------

SESSION IV

CHAIRMAN: R. P. WEBB

16:15-16:45 (WED-10)

INORGANIC NANOTUBES AND FULLERENE-LIKE STRUCTURES (IF): A PROGRESS

REPORT

RESHEF TENNE WEIZMANN INSTITUTE

ISRAEL

16:45-17:15 (WED-11)

NANO-ISLANDS AND NANOWIRES PRODUCED VIA ION IMPLANTATION

FERNANDO ZAWISLAK UNIVERSIDADE FEDERALE RIO

GRANDE SUL, PORTO ALEGRE, BRASIL

17:15 – 17:45 (WED-12)

PROSPECTS OF ION CHANNELING THROUGH CARBON NANOTUBES

ZORAN MISKOVIC UNIVERSITY OF WATERLOO

ONTARIO, CANADA

THURSDAY, DECEMBER 7TH, 2006.

SESSION I

CHAIRMAN: W. K. CHU

8:30 – 9:00 (THU-01)

STRUCTURAL MODIFICATIONS INDUCED IN VARIOUS TYPES OF TARGETS IRRADIATED

WITH ENERGETIC CLUSTER IONS

ANNIE DUNLOP ECOLE POLYTECHNIQUE

FRANCE

9:00 – 9:30 (THU-02)

THE COMPUTER SIMULATION OF ENERGETIC CLUSTERS SOLID

INTERACTIONS

ROGER WEBB UNIVERSITY OF SURREY,

UNITED KINGDOM

9:30 – 10:00 (THU-03)

FRAGMENTATION OF FULLERENES FRANK HARRIS UNIVERSITY OF FLORIDA

USA

10:00 – 10:30 (THU-04)

CLASSICAL-TRAJECTORY MONTE CARLO SIMULATIONS OF THE ELECTRONIC

STOPPING CROSS-SECTION FOR PROTON, ANTIPROTON AND HYDROGEN

PROJECTILES IMPINGING ON HYDROGEN ATOMS

MARIO JAKAS UNIVERSIDAD DE LA LAGUNA

TENERIFE, SPAIN

---------- COFFEE ----------

SESSION II

CHAIRMAN: T. WANG

10:45 -11:15 (THU-05)

THEORETICAL INVESTIGATION OF FRAGMENTATION AND ENERGY

DEPOSITION CROSS-SECTIONS FOR SWIFT ION IMPACT ON SMALL, MODEL

BIOMOLECULES

JOHN SABIN UNIVERSITY OF FLORIDA

USA

11:15 – 11 45 (THU-06)

FRAGMENTATION OF POLYATOMIC MOLECULES IN COLLISIONS WITH ATOMIC

IONS

YNGVE ÖHRN UNIVERSITY OF FLORIDA

USA

AFTERNOON:

VISIT TO TULUM & TANKA

EVENING ( 20:00:HRS )

METTING BANQUET & FESTSCHRIFT ADDRESS.

FRIDAY, DECEMBER 8TH, 2006.

SESSION I

CHAIRMAN: P. KLUTH

9:00-9:30 (FRI-01)

FAST IONS TRACKS IN DIELECTRIC: FROM THE GALACTIC TO THE ATOMIC SCALE

RAUL BARAGIOLA UNIVERSITY OF VIRGINIA

USA.

9:30-10:00 (FRI-02)

SWIFT HEAVY IONS IRRADIATION AS A TOOL FOR CREATING NOVEL

NANOELECTRONIC STRUCTURES

DIETMAR FINK HAHN-MEITNER.INSTITUTE, BERLIN

GERMANY

10:00-10:30 (FRI-03)

MEASUREMENT OF GEOLOGICAL TIME AND TEMPERATURE BASED ON PARTICLE

TRACKS IN NATURAL MINERALS

RAYMOND JOCKHEERE TECHNISCHE UNIVERSITÄT

BERGAKADEMIE FREIBERG, GERMANY

---------- COFFEE ----------

SESSION II

CHAIRMAN: N. STOLTERFOHT

10:45 -11:15 (FRI-04)

TEMPERATURE DISTRIBUTION IN A SWIFT ION INDUCED SPIKE: AN EXPERIMENTAL

APPROACH

G SZENES EOTVOS UNIVERSITY BUDAPEST, HUNGARY

11:15 – 11 45 (FRI-05)

AFM STUDY OF SOME RADIATION EFFECTS ON MATERIALS

C. VAZQUEZ-LOPEZ CENTRO DE INVESTIGACIÓN Y

ESTUDIOS AVANZADOS (INSTITUTO POLITÉCNICO NACIONAL), MÉXICO CITY, MEXICO.

---------- COFFEE ----------

SESSION III

CHAIRMAN: Y. ÖHRN

12:30 – 13:00 (FRI-06)

ELECTRONIC STRUCTURE OF TRANSITION METAL FLUORIDES AND OXIDES

DETERMINED BY RESONANT X-RAY ABSORPTION AND X-RAY EMISSION

SPECTROSCOPIES

JOSÉ JIMÉNEZ-MIER INSTITUTO DE CIENCIAS NUCLEARES,

UNAM, MEXICO CITY, MEXICO

13:00 – 13:30 (FRI-07)

EXPERIMENTAL STUDY OF HIGHLY CHARGED IONS IMPACT ON SOLID

SURFACES

TIESHAN WANG LANZHOU UNIVERSITY,

P.R. CHINA

13:00 HRS. MEETING CLOSING REMARKS

TUE- 01 "SI IMPLANTATION IN SI, RADIATION DAMAGE AND POINT DEFECT ENGINEERING"

Wei-Kan Chu

Department of Physics, and Texas Center for Superconductivity and Advanced Materials University of Houston, Houston, TX 77004-5002, USA

High energy Si self-implantation in Si is a topic with great potential for applications, because

collision, and collision cascade will always produce interstitial and vacancy pairs without any

chemical effect. Due to the forward momentum transfer during collision, the distribution of

interstitials is always deeper then that of the vacancies. After annulations of vacancies and

interstitials in the near vicinity, a vacancy enriched surface region and an interstitial enriched

region near the projected range are developed. The separation of the two regions could be

microns, if MeV implantation were used.

We have developed a point defect engineering (PDE) approach using high-energy ion

bombardments producing vacancies near the surface region of Si where ultra shallow devices

are made. Excessive interstitials near the end of projected range are buried deep inside the

substrate away from the device region. With ever shrinking feature size, it requires a continued

reduction of diffusion lengths of dopants in Si. Normally, one uses very low energy ion

implantation and ultra fast annealing to reduce the dopant diffusion in Si. However, boron ion

implantation undergoes an "anomalous" fast diffusion upon any annealing, which is detrimental

to the ultra-shallow junction formation. Boron diffusion in Silicon is mediated via a interstitial

process. Manipulation of point defects can retard boron diffusion near surface region and

enhance the activation of boron in Si. This non-equilibrium method tailors the diffusivity (not just

diffusion) of boron in silicon and enables the formation of p-type junction as shallow as 10 to 20

nm.

TUE-02 “VIBRATIONAL DYNAMICS AND BOND BREAKING OF H-SILICON”

S.V.S. Nageswara Rao1, S.K. Dixit2,3, G. Lüpke4, N.H. Tolk1 and L.C. Feldman1,2,3

1Department of Physics and Astronomy, 2Interdisciplinary Materials Science Program, 3Vanderbilt Institute of Nano-scale Science and Engineering, Vanderbilt University, Nashville, TN 37235, USA

4Department of Applied Science, College of William and Mary, Williamsburg, VA 23187, USA

Light impurities implanted into or adsorbed onto crystalline solids give rise to localized vibrational

modes, directly observed in infrared absorption. The spectra reveal detailed configurations of the

impurity-substrate bonding configuration. Using intense, time-resolved, infra-red radiation we

have carried out direct measurements of the lifetime of a vibrationally excited state of hydrogen

implanted into silicon. The lifetime, for hydrogen in silicon, is shown to vary over two orders of

magnitude, (10psec-500psec), depending on the defect configuration of hydrogen within the

silicon lattice. We have also measured the stability of these different configurations under ion

bombardment. Surprisingly the stability is a sensitive to relatively subtle differences in structure.

The lifetime and stability is critical in describing a range of solid state phenomena: 1) longevity of

silicon (CMOS) transistors, 2) intensity limitations in solid-state lasers, 3) the non-linear

absorption in IR desorbed (bio) materials, and 4) the interaction of defects with implanted ions.

TUE-03 “ION BEAMS FOR NANO-SCALE SYNTHESIS”*

Daryush ILA

Center for Irradiation Materials,

Department of Physics, Alabama A & M University, 4900 Meridian Street

Normal, AL 35762-1447, USA

We have used ion beam to form nanolayers of nanoscale materials within various host materials.

One system consists of nano-layers (Quantum Well) of Nano-Crystals (Quantum Dots) to

generate optical filters (OF) with variable window as well as to produce highly efficient

thermoelectric generators (TEG). To generate highly efficient TEG, we had to enhance the

electrically conductive, the thermal insulation and increase the Seebeck Coefficient. Some of the

materials selected we had to dope the nano-layers by keV implantation of selected species

followed by MeV bombardment. In some selected materials systems we formed nano-layered

structures by co-deposition followed by MeV bombardment to form nanocrystals. The interaction

of QWs as well as the interaction of QDs results in generation of phonon mini-bands reducing

the thermal conductivity, while increasing the electrical conductivity. We will present our finding

on the dependence of the thermal conductivity (using 3ω technique), electrical conductivity

(using Hall effects), and the Seebeck coefficient as a function of ion bombardment fluence for

several selected materials systems produced in house.

* Support in part by NSF, NASA, and AAMU Research Institute.

TUE-04. “SCALING LAWS FOR GUIDING HIGHLY CHARGED IONS THROUGH NANOCAPILLARIES

IN INSULATING PET POLYMERS”

N. Stolterfoht, R. Hellhammer, D. Fink, and J. Bundesmann.

Hahn-Meitner-Institut Berlin, Glienickerstr. 100, D-14109 Berlin, Germany

Experiments in our laboratory have shown that highly charged ions are guided through

nanocapillaries in insulating PET polymers without changing their initial charge state [1-3]. The

ion guiding was found to be significant when the capillary axis was tilted by an angle up to 20°.

This finding was interpreted as a deflection of the ions near the entrance region of a capillary,

where a significant charge patch is produced in a self-organizing manner [1,4]. The patch is

characterized by the potential U which, in turn, governs the guiding power of the capillaries.

In our previous work [1-3] the capillaries in PET were manufactured by etching ion tracks

produced with fast ions of a few hundred MeV. We used high-Z xenon ions for which the effects

of Rutherford scattering are considerable, resulting in a noticeable angular spread of the

capillary inclination. Recently, we fabricated capillaries with 250 MeV krypton ions for which the

angular spread of the ion tracks was significantly reduced to ~0.4°. With the parallel capillaries

new features can be observed in comparison with our previous measurements.

In this work, we present experiments with the parallel PET capillaries of 200 nm diameter

and 10 µ length. We performed measurements using projectiles with different energies and

charge states, i. e., Ne7+ and Ne9+ at 3-10 keV, Ar13+ at 7-13 keV, and Xe25+ at 25-40 keV. Using

scaling procedures, the results can be summarized to fit one universal curve, which support

previous model assumptions [2,3]. In addition, the data show that the fraction of transmitted ions

remains nearly constant when the current of the incident ions varies by more than an order of

magnitude. This finding indicates that the potential U is nearly constant and is primarily a

quantity characteristic for the geometry and material of the capillary entrance region only.

[1] N. Stolterfoht et al., Phys. Rev. Lett. 88 (2002) 133201 [2] N. Stolterfoht et al., Vacuum 73 (2004) 31 [3] R. Hellhammer et al., Nucl. Instr. Methods B 232 (2005) 235 [4] K. Schiessl, et al. NIM B 232 (2005) 228 and Phys. Rev. A 72 (2005) 62902

TUE-05 “CREATION OF SURFACE NANOSTRUCTURES BY IRRADIATION WITH SLOW HIGHLY

CHARGED IONS”

A.S. El-Said1, W. Meissl1, M.C. Simon1, J.R. Crespo López-Urrutia2, C. Lemell3,

I.C. Gebeshuber1, HP. Winter1, J. Ullrich2, C. Trautmann4, M. Toulemonde5, and F. Aumayr1*

1 Institut für Allgemeine Physik, TU Wien, 1040 Vienna, Austria 2 Max-Planck Institut für Kernphysik, 69029 Heidelberg, Germany 3 Institut für Theoretische Physik, TU Wien, 1040 Vienna, Austria

4 Gesellschaft für Schwerionenforschung (GSI) 64291 Darmstadt, Germany 5 Centre Interdisciplinaire de Recherches Ions Laser (CIRIL), 14070 Caen Cedex 5, France

Upon interaction of highly charged ions (HCI) with solid surfaces a large amount of potential energy is deposited within a very short time (a few femtoseconds) within a nanometer size volume close to the surface [1]. This unique ability of HCI offers a promising way for surface nanostructuring of different materials [2,3]. We present first results on the generation of surface nanostructures by HCI on CaF2 (111) cleaved surfaces.

The CaF2 (111) single crystals were irradiated with slow (E/m < 5 keV/amu) HCI from the Heidelberg-EBIT (electron beam ion trap). As for other ionic fluoride single crystals, ion-induced surface structures in CaF2 are known to be stable in atmosphere at room temperature [4,5]. After irradiation, the crystals were investigated by scanning force microscopy in ambient air. Fig. 1 shows typical AFM topographic images of CaF2(111) after irradiation with 4.4 keV/amu Xe46+ ions. Hillock-like nanostructures protruding from the surface are observed. The AFM images were evaluated with respect to hillock height and width distributions. The number of hillocks per unit area is in good agreement with the applied ion fluence. By using slow HCI in different charge states we find clear evidence that the hillock formation requires a critical potential energy of 14 keV. With increasing potential energy, both the basal diameter and the height of the hillocks become larger. Estimations of the energy density deposited on the atoms indicate that the threshold is linked to a solid-liquid phase transition.

Figure 1: AFM topographic image of a CaF2 single crystal surface after irradiation with 4.4 keV/amu Xe46+ ions. This work has been supported by Austrian Science Foundation FWF and was carried out within Association EURATOM-ÖAW. The experiments were performed at the distributed LEIF-Infrastructure at MPI Heidelberg Germany, supported by Transnational Access granted by the European Project HPRI-CT-2005-026015. [1] F. Aumayr, HP. Winter, Phil. Trans. R. Soc. Lond. A 362 (2004) 77. [2] Y. Baba, et al., Surf. Sci. 599 (2005) 248. [3] F. Aumayr and HP. Winter, e-J. Surf. Sci. Nano-techn. 1 (2003) 171 [4] A.S. El-Said, et al. Nucl. Instr. Meth. B 218, 492 (2004). [5] C. Muller, et al., Nucl. Instr. and Meth. B 191, 246 (2002). * presenting author: e-mail aumayr@iap.tuwien.ac.at

TUE-06 “SPATIAL AND ELECTRONIC CHARACTERIZATION OF NANO-FEATURES CREATED BY HIGHLY CHARGED IONS”

J.M. Pomeroy1, H. Grube1, A.C. Perrella2

1National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA 2US Army Research Laboratory, Adelphi, MD, USA

Atomic scale imaging of a diverse range of surfaces irradiated with highly charged ions (HCIs)

have revealed nanometer size features whose synthesis and structure are poorly understood.

HCIs can carry a significant amount of neutralization energy (51 keV per ion for Xe 44+, used in

most of the results presented) in addition to their kinetic energy. This potential energy amplifies

the violence of the HCI's interaction with the surface by generating massive secondary electron

and sputtered atom yields, etc. This talk will present STM images of surface features observed

on metals with emphasis on the Au(111) surface and the features of the physical structure.

Further, results will be presented from electronic measurements of multilayer systems that

include tunnel junctions that have been irradiated with HCIs. The total conductance of the

junction is observed to increase linearly with the HCI dose, but the rate of increase is

substantially less than a single conduction quantum per ion per spin. Results of electronic

measurements that provide insight into the electronic properties of the HCI modified tunnel

barrier will be emphasized. Cumulative results from spatial and electronic measurements will be

presented and their implications discussed.

TUE-07 “SURFACE MODIFICATIONS OF POLYMERS BY ION BEAMS FOR BIOLOGICAL

APPLICATIONS”

Giovanni Marletta

Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN) – Dipartimento di Scienze Chimiche – Università degli Studi di Catania

Viale A.Doria 6 – 95125 Catania (Italy) Web page: www.unict.it/lamsun/

The need for having a breakthrough in fields relevant to health and safety-like

biocompatible materials, bioelectronics devices, biosensors etc., is the driving force to develop

new performant methods for the controlled modification of surfaces of materials. In particular,

polymers represent the material of choice for most of the desired biological applications, due to

their highly specific properties, including the dynamical behaviour in presence of external stimuli

and the biomimetic mechanical properties.

A welt of competing methods is currently used to modify variable materials thicknesses at

the surfaces of inorganic or polymeric materials. Roughly, we can distinguish three basic areas,

respectively consisting in “wet chemistry” approach to attach specific functional group onto

materials surfaces, deposition of thin and ultrathin films at the materials surfaces and radiation-

based methods to intrinsically modify the chemical and physical structure of the materials of

interest.

Among the irradiation-based techniques, ion beams have been shown to have a number

of intrinsic advantages with respect to other methods, while having an intrinsic complexity. In the

present talk it will be shown that the physics and chemistry of ion beam-polymer interaction

involve different hierarchical levels of surface modification, going from the modification of the

polymer backbone, to the modification of functional groups density at the surfaces and their

distribution at the nanometric scale, the formation of new phases, the formation of nanofeatures

on the surfaces, the modification of the electrical properties, etc...

In recent years it has been shown that ion beams are extremely effective in inducing

controlled modification of the biological response at surfaces, involving not only the modification

of adsorption/adhesion processes of aminoacids, oligopeptides, DNA strands and proteins, but

also affecting in a peculiar way the biochemical mechanism of the cells-surface interaction. In

particular, it can be shown that the biological response of cellular systems critically depends

upon few critical features of the irradiated surfaces as, for instance, the relative weight of the

various components of the surface free energy of the modified polymers and the electrical

properties of the surfaces. Examples will be given on the modified interaction processes of

simple aminoacids as L-lysine, of oligopeptide sequences, of proteins as Human Serum Albumin

and Fibronectin and cellular systems including fibroblasts, osteoblasts and perycites with

irradiated surfaces. Finally, the possibility of achieving the direct patterning of biological systems

by ion beams will be demonstrated.

TUE-08 “COLLECTIVE ELECTRONIC EXCITATIONS AT METAL SURFACES”

V.M.Silkin1, E.V.Chulkov1,2, P.M.Echenique1,2

1Donostia International Physics Center (DIPC), 20018 San Sebastián, Basque Country, Spain. 2Departamento de Física de Materiales, Facultad de Ciencias Químicas, UPV/EHU and Centro Mixto

CSIC-UPV/EHU, 20080 San Sebastián, Basque Country, Spain

The termination of a bulk metal by a surface gives rise to surface-localized collective excitations of the electrons, the so-called surface plasmons [1] During several decades of intensive investigations remarkable progress has been achieved in the understanding of these excitations at metal surfaces [2]. These excitations play an important role in such areas as surface dynamics, surface plasmon (SP) microscopy, SP resonance technology as well as in photonic applications. Despite the progress in the study of these excitations, the quantitative level of agreement between experiment and theory in the description of energy dispersion and lifetime of SP has not been achieved until recently [3] mainly because of difficulties in the incorporation of band structure effect in the evaluation of SP properties [2].

In this contribution we report on the results of parameter-free ab initio calculations of the SP energy and linewidth for some metal surfaces. We investigate the relative impact of band structure and dynamical exchange-correlations on the SP. For comparison we also calculate the SP characteristics by using the jellium model. The results obtained show that even for such nearly-free electron metals good agreement with the experimental SP energy and linewidth in a large range of 2D momenta is found only if both the bulk and surface band structure on the same footing together with dynamical exchange-correlations are taken into account. In particular, three dimensional band structure effects are crucial for the description of the SP linewidth, whereas jellium model fails to reproduce the experimental linewidth for both small and large momenta

Whereas SPs show an optical dispersion, i.e. they always have a finite energy, in general a few eV, they can neither be excited thermally nor do they contribute to the decay of low-energy electrons or phonons.

Recently it was demonstrated theoretically that a new type of collective electron mode on metal surfaces is possible [4]. In contrast to the usual surface plasmon, it has an acoustic dispersion, i.e., has a acoustic linear dispersion at low values of parallel momentum transfer. This low-energy excitation mode was very recently detected on the (0001) surface of beryllium using electron energy loss spectroscopy [5]. Here we report on our detailed ab initio calculations showing that this novel mode is caused by the coexistence at the metal surface of a partially occupied quasi two-dimensional one-particle surface-state band with the underlying three-dimensional bulk electron continuum. The possibility to excite this collective electron mode can lead to new situations at metal surfaces, where many phenomena, such as electron, phonon, and adsorbate dynamics can be significantly influenced by opening of this new low-energy decay channel.

References

[1] R.H.Ritchie, Phys. Rev. 106, 874 (1957). [2] P.J.Feibelman, Prog. Surf. Sci. 12, 287 (1982); M.Rocca, Surf. Sci. Rep. 22, 1 (1995); A.Liebsch, Electronic Excitations at Metal Surfaces (Plenum Press, New York, 1997). [3] V.M.Silkin et al., Phys. Rev. Lett. 93, 176801 (2004). [4] V.M.Silkin et al., Europhys. Lett. 66, 260 (2004). [5] B.Diaconescu et al., submitted

TUE-09 “NANOSCALE OPTICAL MICROSCOPY AND SPECTROSCOPY: NANOPARTICLE

PLASMONICS”

Javier Aizpurua

Donostia International Physics Center, Paseo Manuel Lardizabal 4, Donostia-San Sebastián 20018, Spain

Collective oscillations of valence electrons in metallic materials, also known as plasmons,

determine the optical response of these materials. The energy and strength of these surface

oscillations are a function of the shape, size and coupling of the nanoparticles. With the use of

the boundary element method (BEM), we solve Maxwell's equations to calculate light scattering

and surface modes in nanostructures that are commonly used as hosts and/or samples in

different field-enhanced scanning probe microscopies and spectroscopies. The light scattering

and near field distribution of particles such as nanorings [1], nanorods [2], nanospheres, or

nanodisks are calculated and interpreted in terms of the plasmon modes supported by the

nanosystems. The results are related for each case with different spectroscopic experiments

and connected with the capabilities of these structures to host biomolecules and perform the

corresponding spectroscopy. Special emphasis is placed on the near-touching limit for pairs of

spherical particles to understand recent experiments in the literature. We also study the

electromagnetic response of gold particles when they are coupled to a metallic tip in scattering-

type near field optical microscopy (s-SNOM) [3,4]. We present the analysis of the backscattered

signal and the near field distribution obtained with different tips for gold particles. We obtain

different optical and infrared contrast for different particle size and substrate material. We

associate these differences in contrast to the properties of the tip-particle-substrate coupling.

The understanding of the coupling of the modes in these systems and the consequences for the

local field enhancement are crucial to engineer and design plasmonic devices for detection and

effective optical response.

[1] J. Aizpurua et al. Phys. Rev. Lett. 90, 057401 (2003).

[2] J. Aizpurua et al. Phys. Rev. B. 71, 235420 (2005).

[3] R. Hillenbrand et al. App. Phys. Lett. 83, 368 (2003).

[4] A. Cvitkovic et al. Phys. Rev. Lett. 97, 060801 (2006).

TUE-10 “IRRADIATION EFFECTS ON METALLIC NANOCRYSTALS”

P. Kluth1, B. Johannessen1, R. Giulian1, D. J. Sprouster1, C. S. Schnohr1, L. L. Araujo1,

A. P. Byrne2, G.J. Foran3, D. J. Cookson4, and M. C. Ridgway1

1Department of Electronic Materials Engineering, The Australian National University, Canberra ACT 0200 2 Department of Nuclear Physics/Faculty of Physics, Australian National University, Canberra, Australia

3Australian Nuclear Science and Technology Organization, Menai, Australia 4Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439,

USA

Ion irradiation of metallic nanocrystals (NCs) embedded in SiO2 can lead to a number of different

effects depending on the irradiation conditions. At energies where nuclear stopping is

predominant, structural disorder/amorphisation followed by inverse Ostwald ripening/dissolution

due to ion beam mixing were observed with increasing irradiation fluence. At very high irradiation

energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic

stopping, a shape transformation of the NCs from spherical shapes to elongated rods is

apparent. We will present an overview of our results on these effects on a number of different

materials systems including Au, Cu, and Pt NCs. Structural and morphological characterization

has been performed by transmission electron microscopy (TEM) in combination with advanced

synchrotron based analytical techniques, in particular x-ray absorption spectroscopy (XAS) and

small-angle x-ray scattering. We present evidence for ion irradiation induced amorphisation of

elemental metal NCs attributed to their initially higher energy structural state as compared to

bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO2

interface. In contrast, bulk elemental metals cannot be rendered amorphous by ion irradiation. At

higher irradiation fluences, ion beam mixing is dominant, resulting in a significant alteration of the

NC size distribution consistent with inverse Ostwald ripening and dispersion of a significant

fraction of the metal atoms in the SiO2. The observed shape transformation in the NCs during

swift heavy ion irradiation is governed by the formation of molten tracks in the SiO2 as the ion

passes through the material. It is clearly characterized as a cumulative process and necessitates

a minimum NC size to occur. Potential mechanisms governing the shape change will be

discussed.

TUE-11 “UV-LASER AND ELECTRON IRRADIATION EFFECTS ON SILVER NANOSTRUCTURES”

E. Haro-Poniatowski1*, N. Batina2, M. C. Acosta-García2, M. A. Pohl-Alfaro3, P. Castillo-Ocampo4, C. Ricolleau5, E. Fort5

1) Departamento de Física, 2) Departamento de Química, 3) Departamento de Ingeniería Eléctrica, 4) Laboratorio de Microscopía Electrónica

Universidad Autónoma Metropolitana Iztapalapa, Av. San Rafael Atlixco No. 186 Col. Vicentina, C. P. 09340 México D. F.

5) Laboratoire Matériaux et Phénomènes Quantiques and Laboratoire de Physique du Solide, UMR 7162, CNRS/Université Paris 7 - Denis Diderot, ESPCI, 10 rue Vauquelin, 75005 Paris Cedex, France

The induced changes on silver nanostructures are investigated using a special experimental

procedure consisting in depositing by pulsed laser deposition and subsequently inducing the

changes directly on transmission electron microscopy grids. The nanostructures have different

morphologies, from isolated spherical-like particles to quasi percolated films. The changes can

be induced either by UV laser in air or by electron beam irradiation in situ in the transmission

electron microscope. The induced modifications were investigated using transmission electron

microscopy and atomic force microscopy. Striking effects are observed on quasi percolated films

which are transformed in assemblies of silver nanoparticles. Upon further irradiation the

nanoparticles grow in size. Furthermore the arrangement of these silver nanoparticles

assemblies can be controlled by irradiating the grids through masks, razor edges (1) and

gratings, taking advantage of their respective diffractive properties. A detailed account and

analysis of the observed effects is given in the present work.

(1) Patterning of nanostructured thin films by structured light illumination E. Haro-Poniatowski, J. P. Lacharme, E. Fort, C. Ricolleau Appl. Phys. Lett. 87, 143103, 2005

*email address: haro@xanum.uam.mx

WED-01 “SHINY QUARTZ: CATHODOLUMINESCENCE AFTER ION-IRRADIATION”

K. P. Lieb, P. K. Sahoo1, S. Gasiorek, and J. Keinonen2.

II. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany

Ion implantation is a promising route for doping quartz with luminescent impurity atoms and

growing photoactive nanoparticles of them. The present work focuses on cathodoluminescence

(CL) and epitaxy during or after Na, Rb, Cs, Ge, and Ba ion implantation [1-6] as well as Rb/Ge

double implan-tation [7] in crystalline α-quartz, under the conditions of dynamic, chemical or

laser-induced epitaxy [8]. In addition to the known intrinsic CL bands, which have been

associated with specific defects in the silica matrix, very intense blue or violet bands were found.

They are correlated with the implanted ion species and follow their thermal behaviour. The

quantum efficiency and possible origins of the blue/violet CL emission for various ions and

processing treatments will be discussed [9,10]. Technologically, the case of double Rb/Ge

implantation [8] appears to be very promising since it offers a high CL output and full chemical

epitaxy.

1 Present address: Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Heverlee, Belgium 2 Permanent address: Accelerator Laboratory, University of Helsinki, FI-00014 Helsinki, Finland [1] S. Dhar, et al., Appl. Phys. Lett. 85 (2004) 1341.

J. Appl. Phys. 97 (2004) 014910 [2] P. K. Sahoo, et al., J. Appl. Phys. 96 (2004) 1392 [3] S. Gąsiorek, et al., J. Appl. Phys. 95 (2004) 4705;

Appl. Phys. B84 (2006) 357 [4] J. Keinonen, et al., Appl. Phys. Lett 88 (2006) 261102 [5] S. Gąsiorek, et al., J. Non-Cryst. Solids 352 (2006) 2986 [6] P. K. Sahoo, et al., Appl. Surf. Sci. 252 (2006) 4477 [7] F. Roccaforte, W. Bolse, K. P. Lieb, J. Appl. Phys. 89 (2001) 3611;

K. P. Lieb, in Encyclopedia of Nanoscience and Nanotechnology, vol. 3, H. S. Nalwa, Ed. (2004) 233-251

[8] P. K. Sahoo, et al., Appl. Phys. Lett. 87 (2005) 021105 [9] P. K. Sahoo, S. Gasiorek, S. Dhar, K. P Lieb,

Nucl. Instr. Meth. B249 (2006) 109 [10] K. P. Lieb and J. Keinonen, Contemp. Phys., in press

WED-02 “EFFECT OF ION IRRADIATION AND POST-ANNEALING ATMOSPHERE ON THE

PHOTOLUMINESCENCE INDUCED BY SI NANOCRYSTALS PRODUCED BY HOT IMPLANTATION IN

SIO2”

U.S.Siasa,b, M.Behara, H.Boudinova, E.C.Moreirac

aInstituto de Física, UFRGS, Caixa Postal 15051, 91501-970 Porto Alegre, RS, Brasil

bCentro Federal de Educação Tecnológica de Pelotas, 96015-360, Pelotas, RS, Brasil cInstituto de Física Universidade Federal Unipampa, Bage, RS, Brasil

In the present contribution the photoluminescence (PL) behavior of Si nanocrystals (NCs)

produced by 600 °C Si implantation into SiO2 matrix has been investigated after ion irradiation

and subsequent annealing in Ar or N2 atmosphere.

With this aim we have implanted Si+ ions at 170 keV at a fluence of 1.0 × 1017 Si/cm2.

After annealing at 1100 oC we have observed two PL bands; one centered at 780 and the other

with much higher intensity at 1000 nm. Afterwards we irradiated the samples with 2 MeV Si+ ions

at a fluence of 2.0 × 1013 Si/cm2. Consequently, we have observed a complete PL quenching

due to the Si NCs amorphization as shown by transmission electron microscopy measurements

(TEM). Furthermore we performed a pos-annealing at 900 oC in N2 or Ar atmosphere. As a

consequence the PL signal was recovered, but with strong PL shape modifications.

When the 4 hours annealing in N2 atmosphere was performed the band centered at 1000

nm recovered its original PL intensity, while the shorter wavelength band recovered only 50% of

its original PL value. Additional annealing up to 7.5 hours induces on the low energy band (1000

nm) an increase of its intensity by a factor of two, while the high energy one (780 nm) does not

show any change. Only after 15 h of annealing this PL band recovered the original intensity,

while the one centered at 1000 nm increased 5 times its original PL value.

On the other hand, the 900 oC annealing performed in an Ar atmosphere has induced a

different behavior. The long wavelength band recovered its PL intensity after 4 hours annealing

time, while the one corresponding to the low energy band remains at half of its original value.

After 7.5 hours of annealing the long wavelength band duplicate its intensity, while the short

wavelength band remains at the same value. Further annealing performed for 15 hours have not

induced further changes in the whole PL spectrum.

In the case of Ar, the above described effects can be tentatively explained on the basis of

simple thermal relaxation process produced in the Si/SiO2 interface. On the other hand,

annealing in N2 induces a process of thermal relaxation that is compounded by exchange of

nitrogen with the oxide network.

WED 03 “ STRUCTURAL CHARACTERISTICS OF NANOCRISTALLINE ZRO2 POWDER SOL-

GEL DERIVED FOR LUMINESCENCE APPLICATIONS“

T. Rivera1*, L. Olvera2, J. Azorín2, M. Barrera2, A.M. Soto2, R. Sosa2, J.A.I Díaz1 and C. Furetta1

1Centro de Investigación en Ciencia Aplicada y TecnologíaAvanzada-Legaria, IPN, 11500, México D.F.

México 2Universidad autónoma Metropolitana-Iztapalapa, 11500 México D.F., México,.

Nanocrystalline ceramics are attracting and increasing interest nowadays. Sol gel is a low

temperature method using chemical precursors that produces ceramics and glasses with better

purity and homogeneity than high temperature conventional processes. This new method of

preparation of nanophosphors was recently strongly developed for high efficiency luminescent

devices needs applying still smaller and smaller particles of luminescent materials. There it is

important to retain a high degree of crystallization of ZrO2 and correlated possible concentration

of defects in nanosized particles of nanophosphors. The XRD patterns show that the calcined

material has a strongly monoclinic structure. Thermoluminescent glow curve of ZrO2 show a

glow curve with two peaks. Photoluminescence (PL) spectra of ZrO2 also were obtained.

* Corresponding author: trivera@ipn.mx

WED 04 “DOSE RATE EFFECTS ON THE THERMOLUMINESCENT PROPERTIES OF MWCVD DIAMOND FILM”

S. Gastelum†, E. Cruz-Zaragoza‡, V. Chernov†, R. Melendez†, M. Pederoza-Montero†, and

M. BARBOZA-FLORES*†

†Centro de Investigación en Física, Universidad de Sonora, A. P. 5-088, 83190 Hermosillo Sonora, México

‡Instituto de Ciencias Nucleares UNAM, A. P. 70-543, 04510 México D. F., México

Synthetic CVD diamond, being non toxic and tissue equivalent, has been proposed as a ionizing

radiation passive dosimeter with relevant applications in radiotherapy and clinical dosimetry. In

the present work, the thermoluminescence (TL) properties of microwave assisted chemical

vapor deposition (MWCVD) diamond, 6 µm thick film grown on (100) silicon substrates, were

studied after room temperature γ-irradiation for 2.4, 5.94, 13.1, 20.67, 43.4 and 81.11 Gy/min

dose rates in the range of 0.05 – 10 kGy. At fixed irradiation dose, the TL glow curve shape

changes and the TL efficiency increases as the dose rate increases. However, a TL efficiency

decrease is observed at a 90 Gy dose for dose rate greater than 43.4 Gy/min. A temperature

shift of the maximum intensity of about 10 K is observed for higher dose rate. As the dose

increases, at any dose rate, the peak temperature at the maximum intensity of the TL glow curve

shifted a few degrees K toward the lower temperature side. A computer deconvolution program

allowed us indistinctly to identify the existence of first order kinetics TL peaks at low doses, and

two first order kinetics TL glow peaks at dose higher than 300 Gy. Supralinear and sublinear

dose behavior were found for low and higher dose; respectively, with a significant dependence

on the dose rate. Due to the dose rate dependence of the TL properties of the CVD diamond

sample, it should be taken into consideration for dosimetric applications involving synthetic

diamond.

*Corresponding author: Tel.: +52 662 259 2156; fax: +52 662 212 6649.

E-mail: mbarboza@cajeme.cifus.uson.mx

WED-05 “ION BEAM SYNTHESIS OF QUANTUM DOTS IN INSULATORS” *

H. Bernas

CSNSM-CNRS, Université Paris Sud, 91405 Orsay Campus, France Fabricating metallic or semiconducting nanocrystal arrays in insulators is of interest for their

optical (e.g., plasmonics) or magnetic (e.g., high-density recording media) properties. Ion beam

synthesis has certainly played a role in this area, but basic questions remain. What are the

microscopic mechanisms that control nanocluster growth, determine their density and size

distributions? Can we control these processes in order to tailor the properties? Confronting

irradiation experiments with very different deposited energy densities (photons versus ions), we

demonstrate major analogies with the photographic process and emphasize the role of

chemistry in nanocluster nucleation and growth processes in glasses. Examples are given for

Ag and PbS nanocluster synthesis. In the former, redox modification by irradiation-induced

electron and hole formation affects nucleation. In the latter, charge state differences affect

diffusion and growth. We devised a strategy to produce PbS quantum dots emitting intense

photoluminescence at 1.5 microns. Finally, we show that the log-normal shape of cluster size

distributions signals a loss of information as to the formation process, hence loss of property

control.

* This work was carried out with R. Espiau de Lamaestre (CSNSM-CNRS and Corning Research Center,

Avon, France)

WED-06 “NON-LINEAR OPTICAL SUSCEPTIBILITIES IN THIN METAL-DIELECTRIC MULTILAYERS

GROWN BY PULSED LASER DEPOSITION “

J L Hernández-Pozos.

Laboratorio de Óptica Cuántica, Departamento de Física Universidad Autónoma Metropolitana-Iztapalapa.

Av. San Rafael Atlixco No. 186 Col. Vicentina, C. P. 09340 México D. F MEXICO.

Thin multilayers with metal-dielectric structure have proven to posses higher optical nonlinarities

compared with purely dielectric materials. We present multilayer structures made of

TiO2/Cu/TiO2 grown by pulsed laser ablation. TiO2 layers are growth under an oxygen

atmosphere; otherwise the film stoichiometry is not preserved and shows oxygen deficiency. Cu

layers are grown under pressures of 10—4 mbar.

Because of the periodic modulation in the refractive index and the metallic component,

dielectric/metal/dielectric ( D/M/D ) structures might present high optical nonlinearities that may

be tuned, In preliminary measurements we have observed optical nonlinearities at two different

timescales.

WED-07 “COLOR CENTERS ENVISIONED AS CONFINED QUANTUM SYSTEMS: THE CASE OF F,

F' AND +2F CENTERS*”

J.L. Marín, R. Aceves, R. A. Rosas, S. Grijalva**

Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-088, 83190 Hermosillo,

Son. and Departamento de Física, Universidad de Sonora, Apdo. Postal 1626 83000, Hermosillo, Son. México.

The connection between what nowadays are known as confined quantum systems, i.e., systems

whose dimensions are of the order of a few nanometers and some defects in alkali halides

crystals, known as color centers, is explored in this work within a semicontinuum model, that is,

this peculiar quantum system of nanometric dimensions, is assumed as a cavity of a given

shape in which one or two electrons are trapped, the surrounding material is considered as a

continuum polarizable medium. In this context, for the sake of solving, approximately or exactly,

Schrödinger's equation, the potential felt by the trapped electron(s) can be simply modeled.

Once the potential is specified, the solution of the equation can be found and some physical

magnitudes of interest can be obtained and compared with their respective experimental

measurements. In doing so, we show that this approach constitutes an interesting alternative in

the study of some properties of these kind of defects.

*One of the authors (JLM) dedicate this work to the memory of Professor Carlos Ruiz-Mejía his former

teacher and very close friend and colleague.

**Graduated student at MS program of Departamento de Investigación en Física, Universidad de Sonora.

WED-08 “CHIRAL THIN FILMS: FABRICATION AND PROPERTIES”

Eva Schubert Department of Electrical Engineering, University of Nebraska-Lincoln, U.S.A.

Nanostructures with complex geometries promise a high application potential for instance as optical and photonic materials, magnetic storage devices or sensors. Glancing angle deposition (GLAD) in combination with a computer controlled substrate rotation is a sophisticated method to customize manifold nanostructure varieties. In our work the particle flux is provided by ion beam sputtering and reaches the substrate under an extremely oblique angle-of-incidence (typically 85 deg respective to the normal). This deposition configuration supports a competitive growth mechanism, yielding to highly porous sculptured thin films (STF) consisting of slanted amorphous silicon needles with a diameter from 20 nm to 50 nm. By applying an appropriate substrate rotation during growth, the nanostructure geometry can be tailored. Chevrons and square screws (Fig. 2b and Fig. 2c) are created with a symmetric stepwise substrate rotation of 180 deg and 90 deg, respectively. The fabrication of circular screws (Fig. 2a) and vertical posts is realised by a constant substrate rotation, and the nanostructure geometry depends on the ratio from deposition rate to substrate rotation speed.

Figure 1 Principle of GLAD

Figure 2. Chirial Nanostructures from Si grown by GLAD, (a)

screws, (b) chevrons, (c) sq screws

Sculptured thin film growth on unseeded substrates is determined by self-ordering phenomena yielding to periodic arrangements of ensembles from nanostructures across the substrate, and Periodic sculptured thin films can be also achieved by using prepatterend substrate templates.

Figure 3. STF growth on substrate templates.

This talk will give a survey about the basic experimentally determined structural and physical (mainly optical) properties obtained on sculptured thin films with different chiral geometries (posts, screws, and chevrons). Additionally, examples for the technical use of chiral solid state materials are demonstrated and discussed.

100

a b c

100 nm

surface diffusion

substrate

particle flux

structure shade

+ substrate rotation

WED-09 “THERMALIZED NON-EQUILIBRATED MATTER: FROM MICROSCOPIC SYSTEMS TO

NANOSTRUCTURES”

L. Benet1, M. Bienert1, J. Flores1, S.Yu. Kun2,3, T.H. Seligman1

1Centro de Ciencias FÍsicas, UNAM, Cuernavaca, Morelos, Mexico 2 Facultad de Ciencias, UAEM, Cuernavaca, Morelos, Mexico

3 Nonlinear Physics Center and Department of Theoretical Physics, RSPhysSE, ANU, Canberra, Australia

Thermalization in highly excited quantum many-body systems does not necessarily mean a

complete memory loss of the way the system was formed. One of the manifestations of such a

thermalized nonequilibrated matter is revealed by (i) a strong asymmetry around 900 c.m. of

evaporating yields in nuclear and photonuclear reactions [1,2], and (ii) highly stable rotational

wave packets in heavy-ion collisions [3,4,5] and bimolecular chemical reactions [5,6]. The effect

is described in terms of anomalously slow phase relaxation in highly excited quantum many-

body systems. This effect may pave the way for quantum computing, with a large number of

qubits n ~ 100 - 1000, far beyond the quantum chaos boarder [1,2]. We shall propose and

discuss experimental tests of a formation of the thermalized non-equilibrated matter in

nanostructures, e.g. in atomic clusters and many-electron quantum dots.

[1] J. Flores, S.Yu. Kun, T.H. Seligman, Phys. Rev. E 72, 017201 (2005); quant-ph/0502050.

[2] M. Bienert, J. Flores, S.Yu. Kun, T.H. Seligman, Symmetry, Integrability and Geometry:

Methods and Applications (SIGMA) 2, paper 027 (2006); quant-ph/0602224; and references therein.

[3] S.Yu. Kun, B.A. Robson, A.V. Vagov, Phys. Rev. Lett. 83, 504 (1999).

[4] S.Yu. Kun, L. Benet, L.T. Chadderton, W. Greiner, F. Haas, Phys. Rev. C 67, 011604(R)

(2003); quant-ph/0205036.

[5] L. Benet, S.Yu. Kun, Wang Qi, Phys. Rev. C 73, 064602 (2006); quant-ph/0503046.

[6] L. Benet, L.T. Chadderton, S.Yu. Kun, O.K. Vorov, Wang Qi, \Quantum-classical transition

for an analog of double-slit experiment in complex collisions", to be submitted.

WED-10 “INORGANIC NANOTUBES AND FULLERENE-LIKE STRUCTURES (IF): A PROGRESS

REPORT”

R. Tenne

Department of Materials and Interfaces, Weizmann Institute, Rehovot 76100, Israel

In this presentation a progress report, focused mainly on the results obtained in our lab will be

presented. While the synthesis and study of IF materials from layered metal dichalcogenides, like

WS2 and MoS2 remain a major challenge, some progress with the synthesis of IF structures from

other compounds, like metal oxides and metal halides have been realized. The synthesis of some

new IF materials, like Cs2O, NiBr2 and others will be described.

The study of the mechanical properties of individual WS2 nanotubes will be discussed in some

detail. The agreement between theory and experiment suggests that the nanotubes are of high

crystalline order and their mechanical properties are predictable.

The study of MoS2 nanooctahedra 3-6 nm in size, which can be considered to be the true

inorganic fullerenes of these and many other layered structures, will be discussed. The

agreement between the calculated and experimentally observed structures indicate that the

nanooctahedra are indeed the stable structures in this size range, beyond this size the quasi-

spherical nested MoS2 structures become stable.

Some new potential applications for these and related materials will be discussed in the fields

of friction reduction of various objects; catalysis; rechargeable batteries, coatings, etc. will be

discussed as well. To capitalize on these opportunities, a production facility for up to 100 kg/day

of IF-WS2 is about to start operating soon.

WED-11 “NANO-ISLANDS AND NANOWIRES PRODUCED VIA ION IMPLANTATION”

F. Kremer1, D.L. Baptista1, P.F.P. Fichtner2 and F.C. Zawislak1

1Instituto de Física, UFRGS, Porto Alegre, Brasil

2Departamento de Metalurgia, Escola de Engenharia, UFRGS, Porto Alegre, Brasil

In the first part of this contribution we report results on the formation of Sn and Pb nanoislands at

the SiO2/Si interface. Ions of Sn and Pb are implanted in the SiO2 film, and post-implantation

thermal treatments at the temperature of 1100°C produce a dense array of nanoislands at the

SiO2/Si interface. Our results show that the implantation parameters, the annealing temperature,

atmosphere and time can be used to control the size, the shape, the composition and probably

the uniformity of the created discreet system of nanoislands. The formed nanoclusters and

nanoislands are investigated using a combination of Rutherford backscattering spectroscopy,

transmission electron microscopy (TEM) and high resolution TEM.

The second part reports the formation of self-assembled Ni nanoparticles by ion implantation

and their application as catalytic seeds for the growth of vertically aligned carbon nanotube

(CNT) arrays. By implanting Ni ions at 100-130 keV at doses of 5×1015 and 1×1016 Ni.cm−2

respectively, Ni nanoparticles were formed inside a 450 nm SiO2 film on Si substrates.

Post-annealing treatments at 700, 900 and 1100°C in a N2 atmosphere were performed,

resulting in the formation of self-assembled Ni nanoparticles with mean diameter of 4, 10 and

40 nm respectively. Diluted HF solution was used to etch the SiO2 layer until the nanoparticles

were exposed to the surface. Finally, vertically aligned carbon nanotubes arrays were grown by

PECVD using C2H2 and NH3 gases under controlled conditions. The samples were characterized

via scanning electron microscopy (SEM), high-resolution TEM and atomic force microscopy

(AFM). The spatial distribution as well the diameter and crystallinity of the Ni nanoparticles are

analyzed for each annealing temperature. The CNTs arrays are analyzed in terms of their

density as well as the diameter of the tubes.

WED-12 “PROSPECTS OF ION CHANNELING THROUGH CARBON NANOTUBES”

Zoran L. Miskovic

Department of Applied Mathematics, University of Waterloo,

Waterloo, Ontario, Canada N2L 3G1

Investigation into the properties of carbon nanotubes (CNTs) has been growing at a relentless

rate over the past fifteen years owing to a boundless range of prospective applications of these

unique carbon molecules in nanotechnology. According to some authors, CNTs are nowadays

considered the hottest topic in physics (http://physicsweb.org/articles/news/10/5/4/1). Important

part of this research endeavor includes interactions with energetic particle beams for the purpose

of both analyzing and modifying the atomic structure and electronic properties of CNTs.

In particular, the past decade has witnessed a spur of theoretical activity in modeling and

simulations of ion channeling through either individual CNTs or bundles, or ropes of CNTs in a

wide range of energies, going from ultra-relativistic down to hyper-thermal. It is expected that the

unique mechanical and electronic properties of CNTs, combined with their high aspect ratio and

the nanometer wide channels can offer potentially great advantages for ion channeling in

comparison to crystal channels, such as wider acceptance angles, lower required minimum ion

energies, 3D control of beam deflection, and weaker dechanneling. However, ion channeling

through CNTs has not yet been realized experimentally, and question remains as to whether

such process is feasible for the purpose of anticipated applications.

In addition to reviewing the status of theoretical modeling of ion channeling through CNTs, a

critical assessment of the conclusions coming from theory will be presented and discussed in the

context of planning possible experiments on this process.

THU-01 „STRUCTURAL MODIFICATIONS INDUCED IN VARIOUS TYPES OF TARGETS IRRADIATED

WITH ENERGETIC CLUSTER IONS”

Annie Dunlop

Laboratoire des Solides Irradiés, Ecole Polytechnique, CEA-DRECAM-CNRS,91128 Plaiseau Cedex,

France.

The talk will concentrate on the structural modifications induced around the path of energetic

projectiles. In the high energy range, energy deposition by the projectile occurs mainly via

electronic excitation and ionisation of target atoms. We will show that this energy deposited in

the electronic system can efficiently be converted into atomic movements leading to structural

modifications in all types of targets.

The use of energetic heavy cluster ions allows to increase the density of energy deposited

in electronic processes by orders of magnitude compared to that resulting from GeV heavy ion

slowing down. This allows to create latent tracks in many materials that were considered as

resistant to electronic excitations and to induce a wide variety of phase changes. The talk will

give an overview of such effects.

THU-02 “THE COMPUTER SIMULATION OF ENERGETIC CLUSTER SOLID INTERACTIONS”

Roger Webb.

Surrey Ion Beam Centre, Advanced Technology Institute, University of Surrey, GU12 5LY, UK

There is a growing interest in the application of accelerated clusters and molecular species as

both implantation and analysis tools. Large clusters have been in use for the deposition of films

and the soft landing of bio materials for a number of years now.

More recently the use of fullerene as a sputtering ion in SIMS has lead to a revitalisation of

academic interest in the technique – as witnessed by the recent SIMS XV conference – and a

host of new potential applications in the identification of molecular species and molecular

imaging. The use of even larger clusters employed with electro-spraying techniques has also

been developed as a new analysis technique (DESI) created. The application of giant gas

clusters combining a component of “active” ingredient in a large inert cluster is making a large

impact in the semiconductor world to provide a new method (“infusion doping”) for shallow

junction formation in silicon and for providing a tool for surface smoothing.

It is clear that there are an increasing number of applications of energetic clusters in the

materials world. In this paper computer simulation techniques are employed to investigate why

clusters are of such interest. In particular the role of cluster impacts on molecular desorption will

be investigated and the effects of variable energy deposition for large gas clusters in infusion

doping will be highlighted.

THU-03 “FRAGMENTATION OF FULLERENES”

R. T. Chancey, J. Oddershede, J. R. Sabin, and Frank E. Harris

University or Florida, Niels Bohr Institute, and University of Utah

We have performed classical molecular dynamics simulations of the fragmentation collisions of

neutral fullerenes (C_24, C_60, C_100, and C_240) with a hard wall. We wrote a highly efficient

special-purpose molecular dynamics code to facilitate the study of tens of thousands of collision

trajectories with a broad range of initial orientations and energies. These simulations indicate

the importance of studying a sufficient ensemble of collision events, and enable statistical

analyses of the fragment size distributions. The results are compared with surface-impact

experimental studies of fullerenes and with the fragmentation patterns observed in systems

ranging from meteorites to atomic nuclei.

THU-04 “CLASSICAL-TRAJECTORY MONTE-CARLO CALCULATIONS OF THE ELECTRONIC

STOPPING CROSS-SECTION FOR PROTON, ANTIPROTON AND HYDROGEN PROJECTILES

IMPINGING ON HYDROGEN ATOMS”

Mario M. Jakas1

Departamento de Física Fundamental y Experimental, Electrónica y Sistemas. Universidad de La Laguna. 38205 La Laguna, Tenerife.

Spain

Although Classical Mechanics cannot account for the electronic structure of atoms and

molecules, the present study shows that the stopping cross-section can be calculated, to a high

degree of accuracy, by assuming that electrons are classical particles. In fact, using such an

approach, the electronic stopping cross-section (Se) for protons, anti-protons and hydrogen

projectiles bombarding hydrogen atoms has been calculated and the results are found to

compare remarkably well with both experiments and previous quantum-mechanics calculations.

The dependence of Se upon the initial state of the electron is analyzed. It turned out that Se is

particularly sensitive to the initial eccentricity of the electron orbit. Similarly, an analysis of the

electron trajectory during projectile-target scattering reveals interesting aspects of the stopping

process which may help one to understand the way electrons absorb energy from the incoming

projectile

1 E-mail address: mmateo@ull.es

THU-05 “THEORETICAL INVESTIGATION OF FRAGMENTATION AND ENERGY DEPOSITION CROSS

SECTIONS FOR SWIFT ION IMPACT ON SMALL, MODEL BIOMOLECULES”

John R. Sabin,1 Remigio Cabrera-Trujillo,2 Erik Deumens,1 and Yngve Öhrn1

1. University of Florida, 2. UNAM-Cuernavaca

The subject of the theoretical and computational work presented in this talk is related to damage

of cellular matter caused by energetic, charged particle radiation such as electrons, protons, and

alpha particles. The direct damage to DNA by swift ions is less important than the damage

caused to DNA by intermediate species produced by interaction of the radiation with other

components of the cellular medium such as water and small bio-organic molecules. These

intermediate species include ions, radicals, and electrons, which, by a variety of mechanisms,

can be involved in reactive processes that result in serious damage to DNA and other larger

biomolecules. Here we investigate the interaction of radiation with some small, model

biomolecules using a theoretical scheme known as Electron Nuclear Dynamics (END), which is

time dependant, direct, and non-adiabatic. As no potential surfaces are required in this

approach, the instantaneous coulomb forces among the participating electrons and nuclei steer

the dynamics of the process. The coupling among all electrons and electrons is explicit. The

major advantage of this method is that all possible product channels are considered together,

and all at the same level of approximation, thus increasing the reliability of prediction of product

distributions. The studies reported here involve 3He2+ colliding with small model biomolecules,

such as formaldehyde and glycine, and we discuss the associated fragmentation and energy

deposition cross sections.

Formaldehyde (CH2O) Glycine (H2NCH2COOH)

THU-06 “FRAGMENTATION OF POLYATOMIC MOLECULES IN COLLISIONS WITH ATOMIC IONS”

Yngve Öhrn.

Quantum Theory Project

University of Florida

P.O Box 118431, Gainesville, FL 3211, USA

Reactive encounters of atomic ions with polyatomic molecules at energies in the keV range

commonly falls outside the scope of adiabatic theory. Such processes involves a large number

of sationary electronic states and associated many-dimensional potential energy surfaces

making apparoaches that employ such quantities prohibitively di_cult. Electron Nuclear

Dynamics1 (END)2 o_ers a time-dependent and nonadiabatic approach to molecular processes

that works via instantaneous Coulombic interactions among particpating electrons and atomic

nuclei. A brief presentation of recent advances in this approach to dynamical processes will be

followed by a discussion of results with comparisons to experiment for proton collisions with

hydrocarbon molecules and for proton collisions with water dimers. Calculated and experimental

cross sections and fragmentation patterns for He2+ and He+ collisions with water molecules 3

will also be presented.

This work was supported by NSF grant 0513386. References.

1) Y. Ohrn et.al., in Time-Dependent Quantum Molecular Dynamics, edited by J. Broeckhove and

L. Lathouwers (Plenum, New York, 1992),pp279-292

2) E. Deumens, A. Diz, R. Longo, and Y. Ohrn, Rev. Mod. Phys. 66, 917 (1994)

3) N. Stolterfoht, R. Cabrera-Trujillo, R. Hellhammer, Z. Pesic, E. Deumens, Y. Ohrn, and J. R.

Sabin, Adv. Quantum Chemistry (in press) (2006)

FRI-01 “FAST ION TRACKS IN DIELECTRICS: FROM THE GALACTIC TO THE ATOMIC SCALE”

Raúl A. Baragiola

Laboratory for Atomic and Surface Physics University of Virginia

In a recent commentary§ I addressed the question of what strategy to use when choosing a

research problem, given our finite lives, if we are to have the largest impact. There I recalled

Poincaré advice to look for extreme or limiting situations, going to the infinitely large and the

infinitesimally small. Bridging the extremes, the theme of this talk will be a problem in

astrophysics - the amorphous / crystalline ratio of interstellar dust and their icy mantles,

discussing its necessary cause, high-density ionization tracks, a subject that counted Lew

Chadderton among its pioneers. I will emphasize the incomplete understanding of the so-called

velocity effect in track formation where, for the same stopping power, ions with v < vm, the

velocity of the stopping power maximum, produce more effects (damage, sputtering) that ions

with v > vm. The discussion will be centered in the atomistic aspects of the physical stage of the

energy deposition and will be illustrated with our recent measurements of the velocity effect in

the sputtering of solid oxygen[1].

§ R. A. Baragiola, Some Challenging Unsolved Problems in Atomic Collisions In Solids. Nucl. Instr. Meth.

Phys. Res. B 237 (2005) 520-524

[1] M. Fama, D. A. Bahr, and R. A. Baragiola, to be submitted.

FRI-02 “SWIFT HEAVY ION IRRADIATION AS A TOOL FOR CREATING NOVEL NANOELECTRONIC

STRUCTURES”

D.Fink1, L.T.Chadderton2, W.R.Fahrner3, K.Hoppe4, A. Kiv5, A.Sad5

1Hahn-Meitner-Institute Berlin, Glienicker Str. 100, D-14109 Berlin, Germany 2 Inst. of Advanced Studies, ANU Canberra, GPO Box 4, ACT, Australia

3Chair of Electronic Devices, Inst.of Electrotechnique, Fernuniversität, Hagen, Germany 4South Westfalia University of Applied Sciences, Hagen, Germany

5Ben-Gurion University of the Negev, Israel, P.O.B. 653, Beer-Sheva, 84105, Israel 5 Al-Balqa University- P.O.Box 2041- Amman-11953-Jordan

An overview is given about the strategies to create a novel “Swift-heavy Ion Track Electronics

(SITE)” and an “Electrolytic Electronics with Etched Tracks (E3T)”, by combining swift heavy ion

tracks in thin membranes with conventional semiconductor-based electronic skills and eventually

also with nanoparticles on the one hand, and with electrolytes on the other hand. In this way,

multiparametric and multilevel ambient-sensing and decision-making electronic elements can be

constructed which offer a range of unusual properties.

The most interesting feature in both types of ion track electronics is the frequent occurrence of

two different working states, eventually leading to negative differential resistances (NDRs). NDRs

can show up as well within individual track structures, as via track-to-track interaction; in the latter

case the NDRs are tunable. An interesting consequence of NDRs are self-pulsating tracks. It is

suggested to use structures with NDRs as primary active electronic elements. It is now our aim to

improve the reproducibility of these ion track structures, for reliable technological applications.

FRI-03 “MEASUREMENT OF GEOLOGICAL TIME AND TEMPERATURE BASED ON PARTICLE TRACKS

IN NATURAL MINERALS“

Raymond Jonckheere.

Geologisches Institut, Technische Universität Bergakademie Freiberg, Bernhard-von-Cotta-straße 2, D-09599 Freiberg

Several natural minerals contain trace amounts of uranium. Spontaneous nuclear fission of the isotope 238U leads to the formation of particle (fission) tracks along the trajectories of the ejected nuclear fragments. The lattice damage along a fission track is repaired at elevated temperatures, leading to a gradual reduction of its etchable length, which depends in the first place on the highest temperature that the track has experienced. Thus fission tracks can be thought of as maximum-reading thermometers that are generated throughout geological time. Geological processes that produce temperature variations in a rock, such as magma intrusion, meteorite impact, sediment burial, uplift of mountain ranges due to the collision of tectonic plates or climatic factors, the erosion of plate margins, etc., are so registered in the length distribution of fission tracks. A fission-track length distribution thus provides a geological time and temperature record that is accessible to measurement. Apatite occurs in low concentrations in most rocks and is the mineral whose potential has been most exploited. The apatite grains are mounted in resin, polished and etched. The etchant attacks the damage along the fission tracks at a faster rate than the exposed undamaged apatite surface. This produces etch figures, visible under an optical microscope, whose etchable length reflects the maximum temperature that each track has experienced. Tracks intersecting the polished surface are of little use since their lengths are truncated and thus not a measure of the "true" track length. Track length measurements are for this reason performed on fission tracks confined within the interior of the mineral grains and accidentally etched via a surface-intersecting fission track or a crack. Fission-track T(t)-modelling has supplied valuable information in a string of geological studies but some matters of principle are debated that prevent from placing too literal an interpretation on the palaeo-temperature estimates. During the two decades since its development in the late eighties, T(t)-modelling has been improved through the incorporation of chemical parameters and procedures to account for anisotropic length reduction and through the development of better modelling software. It is nevertheless remarkable that, during all this time and despite ambivalent results, its basic principles have almost never been challenged and that the critical observations that have been expressed in print have met with immediate reprisals. It is no exaggeration to call the present consensus unscientific, and, for this reason, to predict its imminent end and to expect that a detailed and extensive re-examination of the fundamental principles of fission-track T(t)-modelling will dominate research in the coming decade. Several fundamental issues must be re-examined. (1) The resolution of T(t)-modelling, i.e. the limits of palaeo-temperature information contained in the fission-track length distribution, separate from limits implicit in the user-entered modelling constraints. It can be shown that there can exist no pure "data-driven" solution although it is sometimes advocated as the certain outcome of "correct" modelling procedure. (2) The calibration of the annealing equations describing the extent of track-length reduction at fixed (T,t)-conditions. The existing equations have been fitted to data from high-temperature, short-duration experiments on induced tracks in pre-annealed samples. The alternative is to estimate the annealing parameters from length measurements of fossil tracks in borehole samples exposed to (T,t)-conditions inferred from independent evidence. This approach not straightforward and less attractive from a methodological standpoint but it is intolerable that attempts at an independent calibration continue to be opposed, given the questions raised about the extrapolation of lab data to geological timescales. (3) Fission-track counts and length measurements are performed on etched grain mounts with the aid of a high-magnification optical microscope. The biases inherent in the track counts affect the fission-track age and have in part been circumvented by the introduction of age standards but their causes are to a large extent still unclear. The sampling biases associated with track-length measurements have been the subject of recent research but are also still obscure. It is no exaggeration to state that we neither understand what we count nor what we measure. It is important that the principal biases are separated. The "length bias" correction is an essential element of all T(t)-modelling. However, it plots the apparent track densities versus the apparent mean track lengths for different degrees of annealing and it is used to correct both the measured lengths and the measured track densities despite the fact that counts of surface-intersecting tracks and measurements of confined tracks are affected by different biases. (4) T(t)-modelling rests on axioms such as that annealing involves a single process and that a track has no properties other than its mean length (principle of equivalent time) that are to some extent contradicted by the evidence. All these issues must be re-examined. The involvement of track physicists and an understanding of the fundamental processes involved in track formation and repair are of crucial importance in this undertaking.

FRI-04 “TEMPERATURE DISTRIBUTION IN A SWIFT ION INDUCED SPIKE: AN EXPERIMENTAL

APPROACH”

G. Szenes

Department of Materials Physics, Eotvos University, Budapest, Hungary H-1518 Budapest P.O.B. 32, Hungary

The peak temperature and the width of the temperature distribution are key parameters for thermal spike effects. A thorough analysis of existing experimental data on ion-induced latent tracks in insulators allows the unambiguous derivation of the temperature distribution in the spike.

It has been reported in numerous publications that track diameter 2R is controlled by the electronic stopping power Se and tracks are formed only above a threshold value Seo. Earlier, Seo=αc(Tm-Tir) has been found, where c is the specific heat calculated by the Neumann-Kopp’s rule, α is the same constant for all track forming insulators and Tm and Tir are the melting and irradiation temperatures [1]. This is strong evidence that tracks are formed by fast cooling of the ion-induced melt. On the other hand, the track radii satisfy the equation R2=m2ln(Se/Seo), where the peculiarity is, that m is the same constant for any track forming insulator whatever is the energy of the bombarding ions [1]. Combining these two equations leads to a simple expression (Tm-Tir)=(<se>/3αk)exp{- R2/m2} where <se> is the average stopping power per atom and k is the Boltzmann constant.

It can be shown that when the peak temperature of the spike attains its maximum value Tp=<se>/3αk, the melt has the maximum diameter 2r and the width of the distribution is 2r=2R at T=Tm, where T is the local temperature. Thus, when the track radii R are measured in various insulators, the widths of the distributions are obtained at a single Tm temperature in each solid. However, these independent Ti=Tmi, ri=Ri (i=1..n) data pairs satisfy the same Gaussian function with identical parameters at given values of <se> and Tir . This is more than an indication that there must be a close relationship between the temperature distributions in these solids.

We speak about Tm and do not about e.g. the Curie temperatures because Tm has a preferred role for the experimental method which is applied. The temperature distribution is formed in the spike as a result of the interaction of excited electrons with lattice atoms. It is highly important that Tm has no preferred physical meaning in this process. Consequently, if the above Gaussian distribution is valid for Ti=Tmi, ri=Ri (i=1..n) data pairs in various insulators, it must be valid at various other temperatures T Tm, as well. This is possible only if the ion-induced local temperature

distribution is independent of material parameters at the moment when Tp=maximum and it has the form

)1(m

rexp

k3

sTT

2

2e

ir⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧−

α><

+=

in any track forming insulator. There is a velocity effect in the formation of tracks: Seo is reduced for low velocity ions and they form larger tracks than high velocity ions at equal values of Se [2]. Thus, α=αL and α=αH at low and high ion velocities and αL<αH in Eq.(1). Accordingly, when the ion velocity is reduced keeping Se=constant, Tp is increased, however, the variance of the distribution remains constant. This is the physical origin of the velocity effect. The importance of the correct temperature distribution cannot be overemphasized. A typical example is the electronic sputtering in an oxide when thermal spike analyses based on different temperature distributions deduce activation energies differing by an order of magnitude [3]. Finally, the physical consequences of Eq.(1) and the temperature range of its validity are discussed. References [1] G. Szenes, Phys. Rev. B 51, 8026 (1995), J. Nucl. Mat. 336, 81(2005). [2] A. Meftah, et al., Phys. Rev. B 48, 920(1993). [3] G. Szenes, Nucl. Instr. and Meth. B 233, 70 (2005).

FRI-05 “AFM STUDY OF SOME RADIATION EFFECTS ON MATERIALS”

G. Espinosa1., J. I. Golzarri1, C. Vázquez-Lopez2.

1Instituto de Física, UNAM, Apdo. Postal 20-364, México, D.F 2Departamento de Física, CINVESTAV, Apdo. Postal 14-740, México 07000, D.F.

In this work, we show that Atomic Force Microscopy (AFM) is very reliable to study nuclear

tracks on solids. The materials were irradiated with 252Cf fission fragments, with average

energies of 79 and 104 MeV. The results show that each material present quite different effects.

For example, in diamond and quartz it was observed pits and ejected material deposited on

ordered sites. In amorphous silica the ejected material was deposited randomly.

The main aim of this study is to help the understanding of the interaction of the radiation with

insulating materials.

FRI-06 “ELECTRONIC STRUCTURE OF TRANSITION METAL FLUORIDES AND OXIDES

DETERMINED BY RESONANT X-RAY ABSORPTION AND X-RAY EMISSION SPECTROSCOPIES.”

José Jiménez-Mier1, Guillermo M. Herrera-Pérez1, Paul Olalde-Velasco1,. Elizabeth Chavira2,

Ioscani Jiménez3, david L Ederer4, T.A. Schuler4.

1.Instituto de Ciencias Nucleares, UNAM, 2.Instituto de Investigaciones en Materiales, UNAM,

3.Facultad de Química, UNAM, 4.Department of Physics, Tulane University.

We present results of soft x-ray absorption and emission experiments at the transition metal L2,3

edge of TiF4, TiO2, V2O5, VF4, MnF2, MnO, and CoF2. The experiments were carried out at beam

line 8.0.1 of The Advanced Light Source in Berkeley. Incoming photons from an udulator are

monochromatized and then fall into the sample. Total electron yield (TEY) measurements are

used to determine the x-ray absorption spectrum of each sample. At selected values of the

excitation energy we then record x-ray emission spectra. The processes studied are the excitation of a 2p electron into an unoccupied 3d state in the transition metal and its subsequent

decay by x-ray emission. These are therefore studies in which the transition metal ion does not

change its charge, and thus one obtains information about electronic states involved in the

excitation and the decay. This photon-in-photon-out technique allows the determination of the

energy position of the transition metal excited states in the compound. For all compounds we

found an elastic emission peak, one or several inelastic peaks that correspond to decay into d-

excited terms, and broad features that occur because of transitions into charge transfer states.

TiF4, TiO2 and V2O5 are very good examples of ionic compounds in which the transition metal

occurs in a d0 ground configuration. For these compounds we found elastic emission and a

broad valence emission feature. We also found a low energy loss emission feature that

corresponds to production of a charge transfer state. VF4 is a good example of a d1 compound.

For resonant emission of this compound we found the elastic peak, charge transfer peaks and

an inelastic emission peak with an energy loss that corresponds to the excitation energy of the

3d electron from the t2g to the eg orbital. MnO and MnF2 both have a half-filled 3d5 subshell. The

ground state is a high-spin 6A1 term, and the d excitations give an indication of the energy

required to flip a spin in these systems. We find states at energy losses of 3.5 and 5.1 eV in

these compounds. We also obtained emission into charge transfer excited states that are at energy losses of about 13 eV in MnF2 and 9 eV in MnO. Finally, CoF2 is an example of a d7

compound in a high-spin quartet term. The emission spectra show an elastic peak, several

inelastic peaks that correspond to production of spin-flip states, but also to production of higher

quartet terms. The absorption data are compared with the results of ligand-field atomic multiplet

calculations, and the emission data are compared with free-ion Hartree-Fock calculations. The

comparison shows very good agreement between experiment and theory for the d5 and d7

compounds, but it is necessary to explicitly include charge transfer in the calculation to

reproduce the TEY spectra of the d0 and d1 compounds.

FRI-07 “EXPERIMENTAL STUDY OF HIGHLY CHARGED IONS IMPACT ON SOLID SURFACE”*

Tieshan Wang, He Xu, Haibo Peng, Rui Cheng, Jia Yang and Dajie Ding

School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China e-mail: tswang@lzu.edu.cn

Recent experimental studies on the impact of highly charged ion (HCI) on solid surface have

been briefly reviewed in this paper. Some new experimental results about the HCI impact on

metals, Si, SiO2, mica and HOPG are reported. The relative sputtering yields induced by Pbq+

and Arq+ projectiles have been studied correlated to the projectile’s charge state, kinetic energy,

incident angle and target materials. Significantly dependences on the projectiles’ charge state

and incident angle are derived out from the measurement, but the phenomena are different on

various target materials. A dependence on projectile’s velocity is also found, but the trend is

different in case of Pbq+ and Arq+ projectiles. Metals, semiconductor and isolators have shown

different sputtering yield versus projectiles’ parameters. Nano-dots on HOPG samples created

by the impact of Arq+ have been investigated correlated to the charge state from 8+ to 14+,

kinetic energy from 20qev to 20 qkeV, respectively. The diameter and height of nano-dots have

been measured. Both parameters have a wide distribution, while same projectile ion has been

used. The main size of dots depends to the charge state and projectile’s kinetic energy. The

form of nano-dots is mostly unsymmetrical. Some dots double-, tri- and multi-peaks have been

also observed. The further study of the nano-dots created by impact of other projectile ions and

on other material is under going.

* This work has been supported by the Nature Science Foundation of China and the Cuiying talent program of Lanzhou University.