Different strategies for single molecule

detection through nanoplasmonics

Enzo Di Fabrizio - Remo Proietti Zaccaria

Istituto Italiano di Tecnologia (IIT)

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Magna Graecia

University

IIT

Genova

Nanophotonics is the interaction of light with

micro/nanometric structures in order to realize optically

induced phenomena such as:

• light harvesting

• waveguiding (photonic crystals, quasi crystals, fibers, etc.)

• wavefront engineering

• near-field microscopy (STM, SNOM)

• near-field spectroscopy (SERS, TERS, SPPERS)

plasmonics (metallic-like nanodevices)

20 m

a)

b)

100nm

What is NanoPhotonics/Plasmonics?

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Why NanoPhotonics?

2

Device oriented

nanophotonics

Photonics

COMPLEX SYSTEM

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LE

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PLE

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YS

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COMPLEX SYSTEM Co

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Light is fun

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Light is science

4

Micro

machine

Cloaking

device

X-rays zone-plate

Photonic

Crystal (PhC)

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Outline C

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• Planar structures & Photonic crystals

• Metallic structures & Plasmonics

• AFM-Raman: toward few/single molecule detection

• Adiabatic compression in details (not too many though)

• Detection in Attomolar solution concentration

• Artificial Lotus effect

• Computational approach: a very powerful resource

5

• Few photons problem

• Electroporation

• Modulated SPPERS

• Adiabatic electrical generation

• Hot electrons nanoscopy

• THz antennas

• Optical computing

• Opto-mechanics

• Plasmo-catalysis

• Thermo-catalysis

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What is nanofabrication?

6

Bottom-up & Top-Down

approaches

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7 a-Si 2D Photonic Crystal

Coll. F. Pirri group

3D PH. Crys. By X-ray lithography 2D Bragg reflector Si/SiO2 Coll. F. Priolo

Topographic lenses

Planar nanostructures

A little something about Photonic Crystals

8

3D

1D PhC

Light?

2D PhC

n1 n2 n1 n2 n1

Fundamental request: translational periodicity

1D

2D

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Photonic crystals: the cradle of photonics

Ingredients:

• Different materials (no bulk)

• Dielectric or metal (absorption)

• Translational symmetry (1D, 2D, 3D)

What we can do:

• Filters

• Hot spot cavities with high Q factor

• Planar waveguides

• Fibers

• Fano modes

• Extention to quasi-crystals (self-similarity)

• Explain natural phenomena (butterfly color)

• Color changing paints

• Nonlinearity: optical computing

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Metallic standing nanostructures

Elongated dimer

nanostars (flower-

like) patterns were

fabricated with

Electron Beam

Lithography.

H = 0-170 nm IPS = 6-250nm Branch ≈ 70 nm core ≈ 80 nm

Elongated Nanostar (flower-like) dimer pattern

SERS applications

A little something about Plasmonics

11

Surface Plasmon Polaritons (SPP)= surface electromagnetic wave

Light is compressed without changing the carried energy

High spatial resolution (nm scale)

kx~1/

light line

=kc/n

Conservation

law: kx

dielectric

metal

z

x

The problem of optics (but not only): diffraction limit ( /2)

How can we see things at the nanoscale with visible/IR/THz light

(>400nm)?

SPP line: light is

compressed!

bulk bulk SPP

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Outline C

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• Planar structures & Photonic crystals

• Metallic structures & Plasmonics

• AFM-Raman: toward few/single molecule detection

• Adiabatic compression in details (not too many though)

• Detection in Attomolar solution concentration

• Artificial Lotus effect

• Computational approach: a very powerful resource

• Few photons problem

• Electroporation

• Modulated SPPERS

• Adiabatic electrical generation

• Hot electrons nanoscopy

• THz antennas

• Optical computing

• Opto-mechanics

• Plasmo-catalysis

• Thermo-catalysis

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Combination of AFM-Raman spectroscopy

12

Open challenge:

nanodevice on a cantilever

efficiently acting as AFM tip

and as a nanontenna for

Raman scattering.

F

d

Raman & force measurements

Force measurements

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13

01 0 01 3

Mark Stockman,

PRL 93, 137404 (2004)

Electric field

Inte

nsity

Effective refractive index

Phase velocity

14

Adiabatic compression

De Angelis et al., Nature Nanotech. 5,

67 (2010)

Adiabatic compression

Energy at the nanoscale

Nm

erical sim

ula

tion

Calc

ula

tion

benzenethiol

Radial mode

(TM0)

Tip radius < 10nm

High spatial

resolution

5fs

ec r

adia

l excitation

(ba

nd

wid

th: 0

.1P

Hz-0

.85

PH

z, 3

50

nm

-3m

)

Scala

r E

fie

ld

Ve

cto

r E

fie

ld

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Fabrication process: pillar growth

15

Electron Beam

5 Kev, 2 nm spot

Si-N Membrane

gold

Pt precursor gas

100 nm

pillar height 2.5 m

pillar base 100 nm

Tip radius of curvature 10-15 nm

15 nm

16

Single QD Raman spectrum C

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Amine peak estimated 10 NH2

groups (from company linkage

data) maximum 80 NH2 groups

De Angelis et al. Nano Lett., 8 (8), 2321–2327 (2008)

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QDs manipulation and deposition on the NW C

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Adiabatic cone on PhC C

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Gold and Silver cones

Di Fabrizio, E., et al., Italian patent n. TO2008A000693 23.09.2008

5 nm radius

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AFM-Raman spectroscopy C

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Nanodevice on a cantilever

efficiently acting as AFM tip and as

a nanontenna for Raman scattering.

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Optical setup C

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Focal plane on the

cantilever

Focal plane on the tip end

TASC – CBM Trieste

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Raman & AFM: chemical sensing C

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silica

Cantilever with

Nano-Cone

Laser lithography Si/SiO2

(optical image)

10 m

Silicon nanocrystal

SiOx Raman

Band

Si Raman

Band

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Raman & AFM: chemical sensing, coarse scan C

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silica

Silicon nanocrystal

Scan length 2 µm

Scan step ~220 nm

p1 p2 p3 p4 p5 p6 p7 p8 p9 p10

2 m

Cantilever with

Nano-Cone

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Raman & AFM: chemical sensing, fine scan C

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Fine scan along the “wall”.

AFM scan step: 7 nm

110 nm Sensing and topography resolution 5-10 nm

From Raman detailed line shape analysis

we found nano crystal size 5-7 nm

Topography Raman intensity

at 520 cm-1

Simultaneously:

AFM topography

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Selected results C

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Nanocone on biological samples C

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Nanocone performs

exceptionally well on biological

samples in physiological

environment

Lipid bilayers in liquid: 4 nm

thickness. Sharp topography

without shear effects.

Topography on insulin fibrils in

liquid: down to resolution of

protofibrillar structures (3-4 nm).

Only 1 report in literature.

Force spectroscopy

on titin protein

Titin Pulling

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Recent results:SERS on amyloid fibrils (on silicon) C

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1

2

Amyloid fibrils are involved in

Alzheimer disease.

Their characterization by AFM

is widely used, however to

date there are few reports

about their Raman signature.

Here we show that insulin

fibrils on silicon, bear a

Raman signature (1),

compared to the background

(2).

1 um scan (topography)

1

2

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Adiabatic compression: behind the scenes C

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SPP

Ag

Strong field

laser

(visible)

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Adiabatic compression: behind the scenes C

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SPP

Ag

Strong field

laser

(visible)

What kind of source?

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The source C

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x

z

Plane wave

X-polarized

Radial polarization

x

y

z

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3D simulation: radial-like source C

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Adiabatic compression

Field enhancement ~100

Strong localization

500nm

x

z

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3D simulation: longitudinal plane wave X C

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NO Adiabatic compression

Phase dependence

Field enhancement ~20

500nm

x

z

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Summarizing…

Nature Nanotech. 5, 67 (2010)

Adiabatic compression

Energy at the nanoscale

Nm

erical sim

ula

tion

Calc

ula

tion

benzenethiol

Radial mode

(TM0)

Tip radius < 10nm

High spatial

resolution

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Opt. Exp. 19, 22268 (2011)

PRB 86, 035410 (2012)

Opt. Lett. 37, 545 (2012)

Outline C

ort

on

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• Planar structures & Photonic crystals

• Metallic structures & Plasmonics

• AFM-Raman: toward few/single molecule detection

• Adiabatic compression in details (not too many though)

• Detection in Attomolar solution concentration

• Artificial Lotus effect

• Computational approach: a very powerful resource

• Few photons problem

• Electroporation

• Modulated SPPERS

• Adiabatic electrical generation

• Hot electrons nanoscopy

• THz antennas

• Optical computing

• Opto-mechanics

• Plasmo-catalysis

• Thermo-catalysis

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Diffusion limit C

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1 fM analyte concentration

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Question: can the diffusion limit be avoided?

SuperHydrophobicity for analyte concentration

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Evaporation implies

concentration and localization

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Artificial Lotus effect: micropatterned surface C

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• Full controllable size

• High aspect ratio (up to 20 or more)

• Both rigid and flexible substrates

Photolithography combined with Deep RIE

10 m

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Artificial Lotus effect C

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Evaporation of 10 ml of water in few minutes

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Artificial Lotus effect C

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Evaporation of 10 ml of water in few minutes

Few molecules...

and we know where they are!

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Evaporation and concentration (10 Attomolar)

Rhodamine

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Raman detection of Rhodamine on pillars C

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1050 1250 1450 1650 1850

Inte

ns

ity

(a

rb.

un

its

)

Raman shift (cm-1)

Rhodamine 6G

10 l - 10-17 mol/l

Roughly 10 Rhodamine

molecules!

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Combination of Plasmonics and hydrophobic surfaces C

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200 nm

4 m 40 m

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3 m

50 nm

Combination of Plasmonics and hydrophobic surfaces

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m m

m m

Combination of Plasmonics and hydrophobic surfaces

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Selected results C

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Outline C

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• Planar structures & Photonic crystals

• Metallic structures & Plasmonics

• AFM-Raman: toward few/single molecule detection

• Adiabatic compression in details (not too many though)

• Detection in Attomolar solution concentration

• Artificial Lotus effect

• Computational approach: a very powerful resource

43

• Few photons problem

• Electroporation

• Modulated SPPERS

• Adiabatic electrical generation

• Hot electrons nanoscopy

• THz antennas

• Optical computing

• Opto-mechanics

• Plasmo-catalysis

• Thermo-catalysis

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200nm

=514/5

30nm

d: 30nm

-200nm

Signal

Noise

• very high signal to noise ratio ~ 100

• field localization

#1: Few photons sub-wavelenght transmission

Max E ~1.7V/m

Z

Polarization: X

Holes diameter: 80nm

0: 530nm

Period: 1 m

|E| @ z=150nm along x (nm)

--- 514nm

--- 530nm

(Ihole/Ibg)x~1400

and

(Ihole/Ibg)y~120

Very high signal

to-noise ratio !

~E0

Decay of |E| along z (nm)

(side hole)

--- 514nm

--- 530nm

(Ihole/Ibg)x~1400

and

(Ihole/Ibg)y~120

Very high signal

to-noise ratio !

~E0

hole

~10nm 1/e

European project: FOCUS

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200nm

=514/5

30nm

d: 30nm

-200nm

Signal

Noise

• very high signal to noise ratio ~ 100

• field localization

#1: Few photons sub-wavelenght transmission

Max E ~1.7V/m

Z

Polarization: X

Holes diameter: 80nm

0: 530nm

Period: 1 m

|E| @ z=150nm along x (nm)

--- 514nm

--- 530nm

(Ihole/Ibg)x~1400

and

(Ihole/Ibg)y~120

Very high signal

to-noise ratio !

~E0

Decay of |E| along z (nm)

(side hole)

--- 514nm

--- 530nm

(Ihole/Ibg)x~1400

and

(Ihole/Ibg)y~120

Very high signal

to-noise ratio !

~E0

hole

~10nm 1/e

E field travelling through the slab

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Va

Vb

Vc

= electrode

#2: Computational electroporation

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#2: Computational electroporation

DNA is negatively charged

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#3: Modulated SPPERS (Energy/Life) U

nfo

lde

d p

rote

in

Pro

pa

ga

tin

g lig

ht

Fo

lde

d p

rote

in

Lo

ca

lize

d lig

ht

• Logic ports (1/0 unit)

optical computing

• Near/Far-field Spectroscopy

Adia

ba

tic c

om

pre

ssio

n!

1 m

Au

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#4: Electrically generated energy concentrator

Laser approach

a)

Electrical

contribution:

adiabatic

compression

~V Hot

electrons

injection

Wide excitation range Not yet possible

(maximum frequency:

100 GHz;

Visible: 500THz)

b)

Electrical approach

Narrow excitation range

Magnetic

contribution:

spectroscopical

shift

• Near-field

magnetic probe?

• Magnetic

compression?

1≠ 2

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#5: Plasmonic hot electrons nanoscopy

5 m m

=1060nm (1.17eV); P=2.43 m;

d=365nm; Tip radius= 25nm

500nm

Ho

t ele

ctro

ns m

ap

an

d m

orp

ho

log

y m

ap

GaAs: Egap=1.42eV

Highly efficient photon-to-

hot electrons conversion

(>30%)!

(k vector from the cone)

AF

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#6: THz antennas (0.1-10THz) Characteristics of THz:

• can penetrate inside most dielectric materials that may be opaque to

visible light

• has low photon energies that do not cause photoionization in

biological tissues

Applications of THz:

• imaging of plastic/ceramic/semiconductors (e.g, quality control)

• spectroscopy (semiconductors, molecules, DNA, proteins)

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Diffr

action lim

it:

/2

Solu

tion:

resonant

pla

sm

onic

nanoante

nnas

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#7: Optical computing

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Logic gate:

AND

T-shape

antenna:

Fano mode

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#8: Opto-mechanic interactions at the

nanoscale Rb = 60nm

H = 3.5 um

T_polymer = 30nm (SU8)

Rho = 1217.9 Kg/m3 (SU8)

Young_mod = 3.1982*108 (1/10

SU8)

Poisson_ratio = 0.33

Core = 30nm Au

Immagine SEM

da Mario

Applications:

• time (msec) resolved spectroscopy (quality

factor, force spectroscopy, sensing)

• microfluidics

• optofluidics

V

m

V V

V V

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#9: Plasmocatalysis

UV

TiO2

e-

h+

O2

O-2

OH-

*OH

Two main issues:

1) UV light (<5% total) Visible with doping

(nitrogen, tungsten, etc.)

2) High e-h recombination rate & low light

absorption Resonant plasmonic

nanodevices

Bayarri et al., Chem.

Eng. J. 200, 158 (2012)

c)

J. Mater. Chem., 2008,

18, 1858-1864

+ superhydrophobicity!

Al

Nature Nanotech. 247, 8, 2013

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#10: Localized high temperature catalysis

Below 1000 C:

Ag=961 C - Au=1065 C - Al=595 C

Ti=1670 C - Cu=1083 C - Cr=1857 C

Pt= 1768 C

e.m

. field

heat sourc

e

tem

pera

ture

440

300

K

Joule effect:

P =J·E

Rb

Te

mp

era

ture

(K

)

Single gold nanoantenna

=1070nm; P=15 W; Waist=1 m;

L=500nm; W=25nm

Conduction

heat transfer:

P= T·S·k/d,

kair=0.026

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Thank you!

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Extra

Remo Proietti Zaccaria

Istituto Italiano di Tecnologia (IIT)

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Computational/analytical research flow chart

Photonic Crystals Plasmonic

structures

Application:

SPPERS*

*Surface Plasmon Polaritons Enhanced Raman Spectroscopy;

Quasicrystals

Application:

Quasicrystals

fibers

Fundamentals:

Quasicrystals

properties

Fundamentals:

symmetry mode

in slab cavities

Metallic Photonic

Crystals

Fundamentals: High

Q factor & Low

modal volume

Fundamentals:

Adiabatic

devices

Super-long

SPP

SMD project Focus project

Nanoantenna project

Applications:

Super-lenses

Sub-wavelength

sensors

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E2

Computational and analytical instruments

RSoft

• Plane wave expansion (PMW)

• Rigorous Coupled Wave Analysis (RCWA)

• Finite Difference Time Domain (FDTD)

Finite Difference

Ttime Domain

(FDTD)

Lumerical CST

Finite Integrate

Technique (FIT)

Robust but not

versatile

Finite Element

Method (FEM)

Less robust than

CST but very

versatile

Comsol

Mathematica

Analytical tool

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E3

Plasmonic at the DUV range (Life/Energy)

Energy (eV)

Experi

ment

Sim

ula

tion

Al/Al2O3 nanoparticles array

E near-field

Extinction e

ff.

Extinction

4 6 8 10

ACS Nano 2013

5.8eV!

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High temperature catalysis (Env.) Matrix of gold nanoantennas

Localized temperature pattern!

400nm

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KA

US

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013

E5

V V

V V

V V

V V

V V

V=1.1V

V=0.3V

V=0.6V