Nanomaterials and their Optical
Applications
Winter Semester 2013
Lecture 05
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http://www.iap.uni-jena.de/multiphoton
Lecture 05
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Module enrolment & Exams
Do not forget: module enrolment ( within few weeks)
Exam form: oral or written, it depends on the number of students
Examinations date:
Tuesday 11 of February 2013
9-10h30
Website for Lecture Materials
http://www.iap.uni-jena.de/teaching.html
Labwork / HiWi position
Send me your CV / transcript of record and motivations !
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Lecture 05
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Topics oral presentation
1
Topics
Nanodiamonds
2
3
4
5
6
PALM & STORM
STED
Optical to plasmon tweezers
Optofluidics for Energy
Quantum dots and computing
7
Lotus Effects
8
Nanowire as biosensors
9
10
Molecura beam epitaxy and MOCVD for semiconductor nanowires growth
Blue laser diode
11
Upconversion nanoparticles
12
Solid-state nanopores
SPASER :
13
surface plasmon laser ?
14
Sensing with SNOM
15
Sensing with whispering gallery modes.
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Oral presentation
• 15 minutes presentation + 3 minutes question
• Account for 40% of your grade
You will be noted on the following criteria
• 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
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Lecture 05
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Possible time for the presentations
Date
Room
Time
10.12
IAP
12.15
Speaker
Title of the talk
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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Lecture 05
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Outline: Plasmonics
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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Lecture 05
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Why plasmonics ?
The speed of photonics
The size of electronics
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
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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Lecture 05
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Definition of Plasmonics
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
Lycurgus cup (British Museum, London, UK).
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
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Lecture 05
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Concept of 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
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
plasmon polariton resonance positions in vaccum
Bulk metal
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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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Bulk Plasmon
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http://www.chemistry-blog.com/?s=plasmonics
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Bulk Plasmon
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http://www.chemistry-blog.com/?s=plasmonics
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The dielectric constant
• 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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Lecture 05
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Drude model (1900)
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
Dielectric constant:
Strong frequency dependence meaning dispersion
• 1/𝛾 is the relaxation time of 10 fs for noble metals
• For a non-lossy model 𝛾 = 0
The damping constant 𝛾 is related to the average collision time
→interactions with the lattice vibrations: electron-phonon
scattering.
Introduction to surface plasmon theory, J.-J. Greffet
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Lecture 05
http://en.wikipedia.org/wiki/Drude_model
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Concept of polariton
plasmon polariton resonance positions in vaccum
Bulk metal
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Metal surface
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Surface Plasmon Polariton (SPP)
Special case when the charges are
confined to the surface of a metal
SPP only exist for
TM (p) polarization
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http://www.chemistry-blog.com/?s=plasmonics
Lecture 05
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Plasmon
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http://www.chemistry-blog.com/?s=plasmonics
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Plasmon
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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http://www.chemistry-blog.com/?s=plasmonics
Lecture 05
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Plasmon = collective oscillations of electrons
n free electron per unit volume
Gauss theorem:
Newton equation:
ON: Displacement of electrons which cancel the field inside the metal
OFF: electrons inside the metal accelerated by the surface charges
oscillations
Plasma frequency for a film
For a nanosphere
infinite surface
Oscillations due to an electric field caused by all the electrons
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Lecture 05
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Non lossy Drude model (1900)
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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Lecture 05
Coupling of light into surface plasmon
is then tricky…
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Lecture 05
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From bulk to surface plasmons
plasmon polariton resonance positions in vaccum
Bulk metal
Metal surface
Surface Plasmon polariton
SPP are 2D, dispersive EM
waves propagating at the
interface conductor-dielectric
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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.
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From bulk to surface plasmons
plasmon polariton resonance positions in vaccum
Localized surface of a metal particle
• 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
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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Lecture 05
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Lecture 05
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Localized surface plasmon in nanoparticles
No wavevector or special geometry, but absorption of light with the right plasmon band
1. Spheres
• 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
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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
• 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
Ag
Au
Wavelength
400 nm
(blue)
530nm
(green)
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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Lecture 05
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Absorption & Scattering
A famous example is the Lycurgus cup (Roman empire, 4th century AD)f
green color when
observing in
reflecting light
Dark field image : only
the light that is scattered
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it shines in red in
transmitting light
conditions
Direct light image : the resonant
color is absorbed , thus the rest is
transmitted
Lecture 05
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Localized surface plasmon in nanoparticles
1. Spheres
From classical electrodynamic: resonance condition
Polarizability of a sphere:
εr = -2 , true in the visible range for noble metal
Microscopic view: 1 atom
Take the simplest atom: hydrogen
Put it into an electric field
You end up with a dipole moment
Macroscopic view: N atoms


p =αE
where α is the answer of the atom to electric field
the macroscopic dipole moment (per unit volume) is called the POLARIZATION :


P = χ1ε 0 E
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Electric susceptibility is a measure of how easily a
dielectric material can be polarized = εr -1
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Localized surface plasmon in nanoparticles
2. Wires, rods or rices
Prolate spheroid a, b as axis
εr = -2 (wavelength of 400 nm) to =-21.5 (wavelength of 700 nm)
• Two plasmon bands for nanorods: long and short axis
• Transverse mode is close to nanoparticles and longitudinal mode is red shifted
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Lecture 05
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Localized surface plasmon in nanoparticles
No wavevector or special geometry, but absorption of light with the right plasmon band
2. Wires, rods or rices
• Two plasmon bands for nanorods: long and short axis
• Transverse mode is close to nanoparticles and longitudinal mode is red shifted
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Lecture 05
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Localized surface plasmon in nanoparticles
3. Nanoshell
60 nm core radius
20 to 5 nm shell thickness
• 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
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Lecture 05
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Type of nanoantennas
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Lecture 05
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Theoretical models to calculate the radiated field
Dipole approximation
(or quasi-static)
Mie scattering
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Lecture 05
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Light Scattering and Absorption Theory
Extinction cross-section (cm2) =
absorption cs + sctattering cs
1. Dipole approximation (or quasi-static)
particle much smaller than the wavelength
σscat
σabs
total scattered or removed energy rate
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Lecture 05
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Light Scattering and Absorption Theory
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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Lecture 05
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Concept of polariton
plasmon polariton resonance positions in vaccum
Bulk metal
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Metal surface
Localized surface of a metal particle
Lecture 05
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Outline: Plasmonics
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
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Stained glass, Notre Dame
de Paris , 1250
Lecture 05
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Liquid chemical synthesis
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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Lecture 05
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Liquid chemical synthesis
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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Lecture 05
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Under different reactions conditions…
• 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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Lecture 05
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Seed-mediated growth method
J. Phys. Chem. C 2010, 114, 7480–7488
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Lecture 05
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Seed-mediated growth method
J. Phys. Chem. C 2010, 114, 7480–7488
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Lecture 05
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Self-assembly method
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
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http://hyperphysics.phy-astr.gsu.edu
Lecture 05
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Self-assembly method
1. At an interface: water-oil, and let one of the liquid evaporate
2. Molecular linkers
J. Nanosci. Lett. 2012, 2: 10
Linking agent or linkers
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1790 | Analyst, 2009, 134, 1790–1801
Lecture 05
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Self-assembly method
2. Molecular linkers
J. Nanosci. Lett. 2012, 2: 10
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Lecture 05
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Self-assembly method
2. Molecular linkers
J. Nanosci. Lett. 2012, 2: 10
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Lecture 05
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Self-assembly method
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
J. Nanosci. Lett. 2012, 2: 10
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Lecture 05
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Self-assembly method
4. Stimuli responsive self-assembly
Temperature, pH, light, solvent polarity
ACS Nano, VOL. 4 ▪ NO. 7 ▪ 3591–3605 ▪ 2010
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Lecture 05
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Nanofabrication: Direct writing method
1. Focused ion beam milling: drill holes
2. Electron beam lithography
direct-writing, 2D arrays
Three-Dimensional Plasmon Rulers
SCIENCE, p. 1407 VOL 332 17 JUNE 2011
Nature Photonics, 5, 83–90 (2011)
Low throughput, expensive, no large scale fabrication for industry
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Lecture 05
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Nanofabrication: Templates Lithography
1. Optical Lithography
Diffraction limited
More expensive for extreme UV
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Lecture 05
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Nanofabrication: Templates Lithography
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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50
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Nanofabrication: Templates Lithography
PDMS = polydimethylsiloxane
Soft stamp, transparent, chip
Biocompatible, Parallelism
Simplicity, Flexibility
J. Nanotechnol. 2011, 2, 448–458
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Nanofabrication: Templates Lithography
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Muhannad S. Bakir, Microelectronics Research Center
, Georgia Institute of Technology
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Nanofabrication: Templates Lithography
Plasmonic waveguides
metal V-grooves
metal V-grooves
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Muhannad S. Bakir, Microelectronics Research Center
, Georgia Institute of Technology
Lecture 05
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Outline: Plasmonics
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
[email protected]
Stained glass, Notre Dame
de Paris , 1250
Lecture 05
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Applications
1. Field enhancement by plasmon coupling
Interaction of a gold nanoparticle with a single molecule
• 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
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.
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Lecture 05
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Applications: 2. Nanoantennas
Purpose: convert the energy of free
Yagi-Uda antennas
propagating radiation to localized
EM antenna = transducer between
energy, and vice versa
electromagnetic waves and electric currents
Antenna = transducer between free
radiation and localized energy
HF to UHF bands (about 3 MHz to 3 GHz)
High gain: 10 dB
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Lecture 05
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Applications: 2. Nanoantennas
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)
Bow-tie antennas
Yagi-Uda antennas
Antennas for light, L. Novotny, Niek van Hulst,
Nature Photonics 5, 83–90(2011)
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Lecture 05
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Applications: 2. Nanoantennas
• 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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Lecture 05
Applications: 3. Surface enhanced Raman
spectroscopy (SERS)
59
What is Raman scattering ?
Rayleigh = elastic scattering of a photon
Raman = inelastic scattering of a photon
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Lecture 05
Applications: 3. Surface enhanced Raman
spectroscopy (SERS)
60
What is Raman scattering ?
inelastic scattering of a photon
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Lecture 05
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Applications: 3. Surface enhanced Raman
spectroscopy (SERS)
What is Raman scattering ?
http://en.wikipedia.org/wiki/Raman_scattering
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.
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Lecture 05
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Applications: 3. Surface enhanced Raman
spectroscopy (SERS)
Raman scattering
Fluorescence
Infrared absorption
Term paper for Physics
598 OS, Shan Jiang,
University of Illinois
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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Lecture 05
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Applications: 3. Surface enhanced Raman
spectroscopy (SERS)
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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Term paper for Physics 598 OS, Shan Jiang, University of Illinois
Lecture 05
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Applications: 4. Nanotools for medicine
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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Lecture 05
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Applications: 4. Nanotools for medicine
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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Lecture 05
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Applications: 4. Nanotools for medicine
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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Lecture 05
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Applications: 4. Nanotools for medicine
2. Plasmonics biosensors
Binding of molecules between plasmon structures
ACS Nano, 2009, 3 (5), pp 1231–1237
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Lecture 05
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Applications: 4. Nanotools for medicine
3. Plasmon-based optical trapping
Nature Physics 3, 477 - 480 (2007)
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, highthroughput
• Lower fabrication costs,
• Safer platform for chemical,
radioactive or biological studies
because of integration of functionality,
smaller fluid volumes and stored
energies
Plasmon nano-optical tweezers, Nature Photonics, 5, 349, 2011
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Lecture 05
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Applications: 4. nanotools for medicine
4. Thermal therapy
Kennedy et al. Gold-Nanoparticle- Mediated
Thermal Therapies, Small, 2010
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Lecture 05
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Outlook
J. a Fan, C. Wu, K. Bao, J. Bao, R. Bardhan, N. J. Halas, V. N.
Manoharan, P. Nordlander, G. Shvets, and F. Capasso, “Selfassembled 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
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
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Lecture 05
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Non lossy Drude model (1900)
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
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Dispersion of photon
Surface plasmon polariton
Lecture 05