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[email protected] Lecture 05 http://www.iap.uni-jena.de/multiphoton
Nanomaterials and their Optical Applications Winter Semester 2013
Lecture 05
[email protected] Lecture 05
Module enrolment & Exams 2
Do not forget: module enrolment ( within few weeks)
Examinations date:
Tuesday 11 of February 2013 9-10h30
Exam form: oral or written, it depends on the number of students
http://www.iap.uni-jena.de/teaching.html Website for Lecture Materials
Labwork / HiWi position Send me your CV / transcript of record and motivations !
[email protected] Lecture 05
Topics oral presentation 3
Topics 1 Nanodiamonds
2 PALM & STORM 3 STED 4 Optical to plasmon tweezers 5 Optofluidics for Energy 6 Quantum dots and computing
7 Lotus Effects
8 Nanowire as biosensors 9 Molecura beam epitaxy and MOCVD for semiconductor nanowires growth
10 Blue laser diode
11 Upconversion nanoparticles
12 Solid-state nanopores
13 SPASER : surface plasmon laser ?
14 Sensing with SNOM 15 Sensing with whispering gallery modes.
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Oral presentation 4
• Quality of the slides: clear and comprehensive, references included
• Timing: no more than 15 minutes and not less either
• Oral expression: fluent
• Scientific content:
• Answer to questions: precise and short
• 15 minutes presentation + 3 minutes question
• Account for 40% of your grade
You will be noted on the following criteria
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Possible time for the presentations 5
Date Room Time Speaker Title of the talk
10.12 IAP 12.15
12.45
13.15
13.45
27.01 IAP 16.00
16.30
17.00
17.30
4.02 IAP 12.15
12.45
13.15
13.45
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Outline: Plasmonics 6
1. Plasmonics vs Electronics and Photonics
a) Definitions: plasmon, polariton
b) Surface plasmon polariton: Drude Model
c) Localized surface plasmon: nanoparticles, nanorods, nanoshells
d) Theoretical modelling : light scattering theory (Rayleigh and Mie)
2. Fabrication of Plasmonics nanostructures
3. Applications of plasmonics:
Stained glass, Notre Dame de Paris , 1250
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Why plasmonics ? 7
High transparency of dielectrics like optical fibre Data transport over long distances Very high data rate
Nanoscale data storage Limited speed due to interconnect Delay times
The speed of photonics The size of electronics
Brongersma, M.L. & Shalaev, V.M. The case for plasmonics. Science 328, 440-441 (2010).
To replace slow electronic with fast photonic devices
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Definition of Plasmonics 8
Metallic nanostructures = the field of plasmonics
Not the confinment of electrons or holes as in semiconductors dots but • Electrodynamics effect • Modification of the dielectric environment
How does plasmonic material look like ? • Metallic thin film • Metallic nanoparticle • Metallic nanorod • Metallic nanoshell
Different point of view of SURFACE PLASMON: • Electrodynamic: surface wave like in radiowave propagation along the earth • Optics: modes of an interface • Solid-state physics: collective oscillations of electrons
Lycurgus cup (British Museum, London, UK).
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Concept of polariton 9
In metal: coupled state between a plasmon and a photon= plasmon polariton In ionic crystal : coupled state between a phonon and a photon = phonon polariton In semiconductor: coupled state between an electron-hole pair = exciton polariton
Elementary excitations: • Phonons (lattice vibrations) • Plasmons (collective electron oscillations)
Polaritons: Commonly called coupled state between an elementary excitation and a photon = light-matter interaction
plasmon polariton resonance positions in vaccum
Bulk metal Metal surface Localized surface of a metal particle
Some materials are taken from lectures located on L. Novotny’s group website: http://www.photonics.ethz.ch/en/courses/nanooptics.html
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The dielectric constant 12
• ω > ωp → εm→1 → volume plasmon polariton • ω < ωp → εm < 0 → wavevector of light in the medium is imaginary → no propagating
electromagnetic modes in bulk
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Drude model (1900) 13
The model, which is an application of kinetic theory, assumes that the microscopic behavior of electrons in a solid may be treated classically and looks much like a pinball machine, with a sea of constantly jittering electrons bouncing and re-bouncing off heavier, relatively immobile positive ions
Strong frequency dependence meaning dispersion
• 1/𝛾 is the relaxation time of 10 fs for noble metals • For a non-lossy model 𝛾 = 0
Dielectric constant:
http://en.wikipedia.org/wiki/Drude_model Introduction to surface plasmon theory, J.-J. Greffet
The damping constant 𝛾 is related to the average collision time →interactions with the lattice vibrations: electron-phonon scattering.
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Concept of polariton 14
plasmon polariton resonance positions in vaccum
Bulk metal Metal surface
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Surface Plasmon Polariton (SPP) 15
Special case when the charges are confined to the surface of a metal
http://www.chemistry-blog.com/?s=plasmonics
SPP only exist for TM (p) polarization
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Plasmon 17
http://www.chemistry-blog.com/?s=plasmonics
Terahertz range : (3×1011 Hz), and the low frequency edge of the far-infrared light band, 3000 GHz (3×1012 Hz)
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Plasmon = collective oscillations of electrons 18
n free electron per unit volume
ON: Displacement of electrons which cancel the field inside the metal OFF: electrons inside the metal accelerated by the surface charges
oscillations
Gauss theorem:
Newton equation:
Plasma frequency for a film
Oscillations due to an electric field caused by all the electrons
infinite surface For a nanosphere
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Non lossy Drude model (1900) 19
Semi-infinite geometry: Energy and momentum must be conserved : light cannot be coupled directly. Finite geometry: Momentum conservation is possible when light is coupled to the localized plasmon excitations of a small metal particle = optical antennas resonances
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From bulk to surface plasmons 21
plasmon polariton resonance positions in vaccum
Bulk metal Metal surface Localized surface of a metal particle
Surface Plasmon polariton SPP are 2D, dispersive EM waves propagating at the interface conductor-dielectric
Localized surface plasmon LSP are non-propagating excitations of the conduction electrons of a metallic nanostructure coupled to an EM field.
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From bulk to surface plasmons 22
plasmon polariton resonance positions in vaccum
Localized surface of a metal particle
Localized surface plasmon LSP are non-propagating excitations of the conduction electrons of a metallic nanostructure coupled to an EM field.
• The curved surface of the nanostructure allows the excitation of the LSP by 3D light
• The resonance falls into the visible region
for Au and Ag nanoparticles
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23
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Localized surface plasmon in nanoparticles 24
No wavevector or special geometry, but absorption of light with the right plasmon band
• Absorption within a narrow wavelength range • The maximum of absorption depends on the size, the shape of the nanoparticles
and the surrounding medium • Small shift for particle smaller than 25 nm, red shift for bigger nanoparticles
1. Spheres
J. a Fan, C. Wu, K. Bao, J. Bao, R. Bardhan, N. J. Halas, V. N. Manoharan, P. Nordlander, G. Shvets, and F. Capasso, “Self-assembled plasmonic nanoparticle clusters.,” Science, vol. 328, no. 5982, pp. 1135–8, May 2010.
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Absorption & Scattering 25
• Light passing through a typical 30nm spherical silver (Ag) colloid appears yellow-green due to the fact that silver particles of this size absorb light in the violet-blue region.
• Spherical gold (Au) nanoparticle colloids of similar sizes appear red, absorbing light maximally in the green region (Stockman Physics Today 2011).
Extinction = absorption + scattering but scattering dominate for small particle
Wavelength 400 nm (blue)
530nm (green)
Ag Au
Dark field image : only the light that is scattered
Direct light image : the resonant color is absorbed , thus the rest is transmitted
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Absorption & Scattering 26
Dark field image : only the light that is scattered Direct light image : the resonant
color is absorbed , thus the rest is transmitted
A famous example is the Lycurgus cup (Roman empire, 4th century AD)f
green color when observing in reflecting light
it shines in red in transmitting light conditions
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Localized surface plasmon in nanoparticles 27
1. Spheres
Take the simplest atom: hydrogen Put it into an electric field
where α is the answer of the atom to electric field
Microscopic view: 1 atom
Macroscopic view: N atoms
p Eα=
You end up with a dipole moment
the macroscopic dipole moment (per unit volume) is called the POLARIZATION :
Electric susceptibility is a measure of how easily a dielectric material can be polarized = εr -1 1 0P Eχ ε=
From classical electrodynamic: resonance condition
εr = -2 , true in the visible range for noble metal
Polarizability of a sphere:
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Localized surface plasmon in nanoparticles 28
• Two plasmon bands for nanorods: long and short axis • Transverse mode is close to nanoparticles and longitudinal mode is red shifted
2. Wires, rods or rices Prolate spheroid a, b as axis
εr = -2 (wavelength of 400 nm) to =-21.5 (wavelength of 700 nm)
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Localized surface plasmon in nanoparticles 29
No wavevector or special geometry, but absorption of light with the right plasmon band
• Two plasmon bands for nanorods: long and short axis • Transverse mode is close to nanoparticles and longitudinal mode is red shifted
2. Wires, rods or rices
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Localized surface plasmon in nanoparticles 30
• For a constant core, a thinner shell shift the plasmon resonance to the red • For a constant core/shell ratio, small particles predominantly aborbs light and big
particles scattered light. Over the dipole limit, multiple plasmon resonance occurs • A broad spectral region is covered
3. Nanoshell
60 nm core radius 20 to 5 nm shell thickness
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Type of nanoantennas 31
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Theoretical models to calculate the radiated field 32
Mie scattering
Dipole approximation (or quasi-static)
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Light Scattering and Absorption Theory 33
1. Dipole approximation (or quasi-static) particle much smaller than the wavelength
Extinction cross-section (cm2) = absorption cs + sctattering cs
σscat σabs
total scattered or removed energy rate
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Light Scattering and Absorption Theory 34
2. Mie scattering
• Maxwell's equations are solved in spherical co-ordinates through separation of variables
• The incident plane wave is expanded in Legendre polynomials so the solutions inside and outside the sphere can be matched at the boundary
• Bessel and Hankel functions are solution are also used in the complex expression for simplification
Legendre polynomials
Bessel and Hankel functions
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Concept of polariton 35
plasmon polariton resonance positions in vaccum
Bulk metal Metal surface Localized surface of a metal particle
[email protected] Lecture 05
Outline: Plasmonics
36
2. Fabrication of Plasmonics nanostructures
• Chemical synthesis
• Single nanoparticles
• Self assembly of nanoparticles
• Nanofabrication
3. Applications of plasmonics:
Field enhancement by plasmon coupling
Optical antennas
Field enhanced vibrational spectroscopy
Nano-tools for medicine
Stained glass, Notre Dame de Paris , 1250
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Liquid chemical synthesis 37
Before the addition of the reducing agent, the gold is in solution in the Au+3 form. When the reducing agent is added, gold atoms are formed in the solution, and their concentration rises rapidly until the solution exceeds saturation. Particles then form in a process called nucleation. The remaining dissolved gold atoms bind to the nucleation sites and growth occurs.
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Liquid chemical synthesis 38
Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.
Turkevich method hot chlorauric acid with small amounts of sodium citrate solution The colloidal gold will form because the citrate ions act as both a reducing agent, and a capping agent.
J. Turkevich, P. C. Stevenson, J. Hillier, "A study of the nucleation and growth processes in the synthesis of colloidal gold", Discuss. Faraday. Soc. 1951, 11, 55-75
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Under different reactions conditions… 39
• Temperature : 120° to 190°, transition between
regular and irregular shapes
• Molar ratio between the materials
• Surfactants: organic compounds that are amphiphilic,
meaning they contain both hydrophobic groups (their
tails) and hydrophilic groups (their heads), lower the
surface tension of a liquid, e. g. CTAB
• Precursors: chemical compound preceding another,
like the GOLD SEEDS
SCIENCE VOL 298 13 DECEMBER 2002 p. 2177
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Self-assembly method 42
Possible Forces
• Covalent : sharing a pair of electrons
• Ionic: transfer of electrons
• Metallic: strong bond
• Hydrogen: simplest covalent bond
• coordination bonds
• van der Waals : electrostatic forces
• casimir, π-π
• hydrophobic
• colloidal
• capillary forces http://hyperphysics.phy-astr.gsu.edu
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Self-assembly method 43
1790 | Analyst, 2009, 134, 1790–1801 Linking agent or linkers
1. At an interface: water-oil, and let one of the liquid evaporate
2. Molecular linkers J. Nanosci. Lett. 2012, 2: 10
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Self-assembly method 44
2. Molecular linkers
J. Nanosci. Lett. 2012, 2: 10
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Self-assembly method 45
2. Molecular linkers
J. Nanosci. Lett. 2012, 2: 10
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Self-assembly method 46
J. Nanosci. Lett. 2012, 2: 10
3. Biomediated self-assembly
DNA, proteins, Viruses, Bacteria
4. Template directed self-assembly external forces that had been placed by design elements are used in forming the self-assembled structures
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Self-assembly method 47
ACS Nano, VOL. 4 ▪ NO. 7 ▪ 3591–3605 ▪ 2010
4. Stimuli responsive self-assembly
Temperature, pH, light, solvent polarity
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Nanofabrication: Direct writing method 48
SCIENCE, p. 1407 VOL 332 17 JUNE 2011
2. Electron beam lithography
direct-writing, 2D arrays
Three-Dimensional Plasmon Rulers
1. Focused ion beam milling: drill holes
Nature Photonics, 5, 83–90 (2011)
Low throughput, expensive, no large scale fabrication for industry
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Nanofabrication: Templates Lithography 49
1. Optical Lithography
Diffraction limited More expensive for extreme UV
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Nanofabrication: Templates Lithography 50
50
1. Optical lithography: Plasmonic Nanolithography
Plasmonic Nanolithography, Werayut Srituravanich,Nicholas Fang,Cheng Sun,Qi Luo, and, and Xiang Zhang, Nano Letters 2004 4 (6), 1085-1088
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Nanofabrication: Templates Lithography 51
51 J. Nanotechnol. 2011, 2, 448–458
PDMS = polydimethylsiloxane Soft stamp, transparent, chip Biocompatible, Parallelism Simplicity, Flexibility
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Nanofabrication: Templates Lithography 52
Muhannad S. Bakir, Microelectronics Research Center , Georgia Institute of Technology
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Nanofabrication: Templates Lithography 53
Muhannad S. Bakir, Microelectronics Research Center , Georgia Institute of Technology
metal V-grooves
Plasmonic waveguides
metal V-grooves
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Outline: Plasmonics
54
6. Fabrication of Plasmonics nanostructures
• Chemical synthesis
• Single nanoparticles
• Self assembly of nanoparticles
• Nanofabrication
7. Applications of plasmonics:
Field enhancement by plasmon coupling
Optical antennas
Field enhanced vibrational spectroscopy
Nano-tools for medicine
Stained glass, Notre Dame de Paris , 1250
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Applications 1. Field enhancement by plasmon coupling
55
S. Kühn, U. Håkanson, L. Rogobete, and V. Sandoghdar, “Enhancement of Single-Molecule Fluorescence Using a Gold Nanoparticle as an Optical Nanoantenna,” Physical Review Letters, vol. 97, no. 1, pp. 1-4, Jul. 2006.
• Plasmon resonance = local enhancement of the electric field, increased absorption of a molecule
• Non planar field distribution matching a molecular assembly
• Fluorescence lifetime is decreased thus the molecule returns sooner to its ground state
Interaction of a gold nanoparticle with a single molecule
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Applications: 2. Nanoantennas 56
Yagi-Uda antennas EM antenna = transducer between electromagnetic waves and electric currents
HF to UHF bands (about 3 MHz to 3 GHz) High gain: 10 dB
Purpose: convert the energy of free propagating radiation to localized energy, and vice versa Antenna = transducer between free radiation and localized energy
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Applications: 2. Nanoantennas 57
Characteristic dimensions of an antenna are of the order of the radiation wavelength Optical antennas on the order of nanometers For a cell phone: λ/100 (for a cell phone, λ ~ 30 cm, for optics 5 nm)
Antennas for light, L. Novotny, Niek van Hulst, Nature Photonics 5, 83–90(2011)
Bow-tie antennas Yagi-Uda antennas
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Applications: 2. Nanoantennas 58
• all parts of the antennas are multiple or fraction of the em radiation λ
• electrons in metals do not respond to the wavelength λ of the incident radiation but to an effective wavelength λeff :
Geometric constant: n1 n2 Plasma wavelength
Metal not ideal (conductivity drops at the nanoscale) but carbon nanotubes or graphene
1. Photodetection and photovoltaics Increased absorption cross-section thus reduce the dimension, power consumption
2. Nanoimaging 3. Building blocks for data processing
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Applications: 3. Surface enhanced Raman spectroscopy (SERS)
59
What is Raman scattering ?
Raman = inelastic scattering of a photon
Rayleigh = elastic scattering of a photon
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Applications: 3. Surface enhanced Raman spectroscopy (SERS)
60
inelastic scattering of a photon
What is Raman scattering ?
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Applications: 3. Surface enhanced Raman spectroscopy (SERS)
61
The Raman effect corresponds to the absorption and subsequent emission of a photon via an intermediate quantum state of a material. The intermediate state can be either a "real", or a virtual state. The Raman interaction leads to two possible outcomes:
• the material absorbs energy and the emitted photon has a lower energy than the absorbed photon. This outcome is labeled Stokes Raman scattering. • the material loses energy and the emitted photon has a higher energy than the absorbed photon. This outcome is labeled anti-Stokes Raman scattering.
http://en.wikipedia.org/wiki/Raman_scattering What is Raman scattering ?
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Applications: 3. Surface enhanced Raman spectroscopy (SERS)
62
Term paper for Physics 598 OS, Shan Jiang, University of Illinois
Raman scattering Fluorescence Infrared absorption
Fluorescence : the incident light is completely absorbed and the system is transferred to an excited state from which it can go to various lower states only after a certain resonance Raman effect : can take place for any frequency of the incident light not a resonant effect
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Applications: 3. Surface enhanced Raman spectroscopy (SERS)
63
Term paper for Physics 598 OS, Shan Jiang, University of Illinois
Internal total reflection for the momentum conservation
15 orders of magnitude enhancement
From an enhanced electric field = plasmon resonance
Chemical enhancement too (factor of 200 on non
metallic substrate) !
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Applications: 4. Nanotools for medicine 64
Two combined effects: 1. Optical property: plasmon resonance 2. Thermal property : remaining energy HEAT
Heat generated in four different colloidal gold nanoparticles of same volume and fixed intensity
Metal particle = point-like sources
of either light or heat
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Applications: 4. Nanotools for medicine 65
1. Temperature mapping
Technique to locally probe the stationary temperature of the medium surrounding nano heat-sources including those formed by plasmonic nanostructures
2 March 2009 / Vol. 17, No. 5 / OPTICS EXPRESS 3291
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Applications: 4. Nanotools for medicine 66
2. Plasmonics biosensors
Engineering nanosilver as an antibacterial, biosensor and bioimaging material, Current Opinion in Chemical Engineering Volume 1, Issue 1, October 2011, Pages 3–10
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Applications: 4. Nanotools for medicine 67
2. Plasmonics biosensors
ACS Nano, 2009, 3 (5), pp 1231–1237
Binding of molecules between plasmon structures
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Applications: 4. Nanotools for medicine 68
3. Plasmon-based optical trapping
Nature Physics 3, 477 - 480 (2007)
Plasmon nano-optical tweezers, Nature Photonics, 5, 349, 2011
Towards an integrated plasmonic platform for bio-analysis
• Low fluid volumes (less waste, lower reagents costs and less required sample Faster analysis and response times due to short diffusion distances, fast heating, high surface to volume ratios, small heat capacities.
• Compactness • Massive parallelization, high-
throughput • Lower fabrication costs, • Safer platform for chemical, radioactive or biological studies because of integration of functionality, smaller fluid volumes and stored energies
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Applications: 4. nanotools for medicine 69
4. Thermal therapy
Kennedy et al. Gold-Nanoparticle- Mediated Thermal Therapies, Small, 2010
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Outlook 70
H. Atwater, The promis of Plasmonics, Scientific Amercian, 2007
Brongersma, M.L. & Shalaev, V.M. The case for plasmonics. Science 328, 440-441 (2010).
D. W. Hahn, Light scattering theory, Notes, July 2009
J. a Fan, C. Wu, K. Bao, J. Bao, R. Bardhan, N. J. Halas, V. N. Manoharan, P. Nordlander, G. Shvets, and F. Capasso, “Self-assembled plasmonic nanoparticle clusters.,” Science, vol. 328, no. 5982, pp. 1135–8, May 2010.
S. Kühn, U. Håkanson, L. Rogobete, and V. Sandoghdar, “Enhancement of Single-Molecule Fluorescence Using a Gold Nanoparticle as an Optical Nanoantenna,” Physical Review Letters, vol. 97, no. 1, pp. 1-4, Jul. 2006.
• Choose your topic and the date of the presentation • Discuss it at the seminar next week
[email protected] Lecture 05
Non lossy Drude model (1900) 71
Surface plasmon polariton
Dispersion of photon
Dispersion relation = solution of Maxwell equation with boundary conditions
o Negative permittivity o SPP wavevector always larger than
photon ->coupling of light is then tricky in planar structure to match the wave vector : Subwavelength scatterer Periodic grating Evanescent field
o Large tunability of the dispersion but propagation losses