Nanomaterials and their Optical Applications · 2013-11-12 · Nanomaterials and their Optical...

[email protected] Lecture 05 http://www.iap.uni-jena.de/multiphoton

Nanomaterials and their Optical Applications Winter Semester 2013

Lecture 05

[email protected]

[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 !


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.


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


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


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


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


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).


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


Bulk Plasmon 10

http://www.chemistry-blog.com/?s=plasmonics


Bulk Plasmon 11



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


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.




Bulk metal Metal surface


Surface Plasmon Polariton (SPP) 15

Special case when the charges are confined to the surface of a metal


SPP only exist for TM (p) polarization


Plasmon 16



Plasmon 17


Terahertz range : (3×1011 Hz), and the low frequency edge of the far-infrared light band, 3000 GHz (3×1012 Hz)


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


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


Coupling of light into surface plasmon is then tricky…

20


From bulk to surface plasmons 21



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.


From bulk to surface plasmons 22


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


23


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.


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


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



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:



• 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)



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



• 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


Type of nanoantennas 31


Theoretical models to calculate the radiated field 32

Mie scattering

Dipole approximation (or quasi-static)


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


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


Outline: Plasmonics

36


• Chemical synthesis

• Single nanoparticles

• Self assembly of nanoparticles

• Nanofabrication


Field enhancement by plasmon coupling

Optical antennas

Field enhanced vibrational spectroscopy

Nano-tools for medicine



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.


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


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


Seed-mediated growth method 40

J. Phys. Chem. C 2010, 114, 7480–7488


Seed-mediated growth method 41

J. Phys. Chem. C 2010, 114, 7480–7488


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



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



2. Molecular linkers

J. Nanosci. Lett. 2012, 2: 10



2. Molecular linkers





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



ACS Nano, VOL. 4 ▪ NO. 7 ▪ 3591–3605 ▪ 2010

4. Stimuli responsive self-assembly

Temperature, pH, light, solvent polarity


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


Nanofabrication: Templates Lithography 49

1. Optical Lithography

Diffraction limited More expensive for extreme UV



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



51 J. Nanotechnol. 2011, 2, 448–458

PDMS = polydimethylsiloxane Soft stamp, transparent, chip Biocompatible, Parallelism Simplicity, Flexibility



Muhannad S. Bakir, Microelectronics Research Center , Georgia Institute of Technology



Muhannad S. Bakir, Microelectronics Research Center , Georgia Institute of Technology

metal V-grooves

Plasmonic waveguides

metal V-grooves


Outline: Plasmonics

54


• Chemical synthesis

• Single nanoparticles

• Self assembly of nanoparticles

• Nanofabrication


Field enhancement by plasmon coupling

Optical antennas

Field enhanced vibrational spectroscopy

Nano-tools for medicine



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


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



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



• 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


Applications: 3. Surface enhanced Raman spectroscopy (SERS)

59

What is Raman scattering ?

Raman = inelastic scattering of a photon

Rayleigh = elastic scattering of a photon



60

inelastic scattering of a photon

What is Raman scattering ?



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 ?



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



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) !


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



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



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



2. Plasmonics biosensors

ACS Nano, 2009, 3 (5), pp 1231–1237

Binding of molecules between plasmon structures



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


Applications: 4. nanotools for medicine 69

4. Thermal therapy

Kennedy et al. Gold-Nanoparticle- Mediated Thermal Therapies, Small, 2010


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


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

Nanomaterials and their Optical Applications · 2013-11-12 · Nanomaterials and their Optical...

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