R. Bachelot, H. Ibn-El-Ahrach1, O. Soppera2 , A. Vial1 ,A.-S. Grimault1, G. L - PowerPoint PPT Presentation

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R. Bachelot, H. Ibn-El-Ahrach1, O. Soppera2 , A. Vial1 ,A.-S. Grimault1, G. L

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Title: R. Bachelot, H. Ibn-El-Ahrach1, O. Soppera2 , A. Vial1 ,A.-S. Grimault1, G. L


1
Spectral degeneracy breaking in plasmon resonance
of single metal nanoparticles by nanoscale
near-field photopolymerization
  • R. Bachelot, H. Ibn-El-Ahrach1, O. Soppera2 ,
    A. Vial1 ,A.-S. Grimault1, G. Lérondel1, J.
    Plain1 and P. Royer1
  • 1 Laboratoire de Nanotechnologie et
    dInstrumentation Optique, Institut Charles
    Delaunay. FRE CNRS 2848. Université de
    Technologie de Troyes, France
  • 2 Département de Photochimie Générale ,Université
    de Haute-Alsace Mulhouse, France

2
Tuning plasmon resonance of metallic
nanoparticles (MRS bulletin May 2005, Vol. 30,
N5)
  • Geometry shape and size
  • Rods, stars, triangles
  • Chemical synthesis / e-beam lithography
  • Single particle coupling (dimers,
    trimers,chains,..)
  • Core/shell approach
  • Ex Nanorice
  • (Rice University)
  • Effective refractive index (polymer coating,
    surrounding medium)
  • Nanosensors
  • But so far only isotropic modification (symmetry
    was kept)

3
Based on local isomerization
4
The Photopolymer formulation
hn
Eosin absorption spectrum
composition Initiator ( Eosin Y)
Co-initiator (MDEA) Monomer
(PETIA)
Radical polymerization
5
The photopolymer formulation
  • Formulation properties
  • Polymerization threshold energy
  • Refractive index
  • 1.48 for 0 reticulation
  • (liquid formulation)
  • 1.52 for 100 reticulation
  • (Crosslinked polymer)

6
A key parameter the threshold energy. Far field
characterization of this parameter
Ar laser 515nm
7
Far field characterization of the
Photopolymerization
Experimental characterization of the threshold
energy of polymerization
Threshold polymerization energy
(a)AFM image of a polymer grating obtained after
12mJ/cm²
(b)AFM image of a polymer grating obtained after
20mJ/cm²
Threshold energy value 10 mJ/cm²
8
Near field photopolymerization
  • Principle
  • Incident energy Eilt Ethreshold

Overcoming the threshold energy by local
enhancement of the optical near field
9
Near field illumination
  • Experimental approach
  • 1) E-beam lithography
  • 4) Monomer removal (Rinsing)
  • 5) Characterization - AFM
  • -Spectroscopy
  • 2) Coating (drop)
  • 3) Illumination

Array of Ag particles
Diameter 70nm height 50nm
D2,5mW/cm2 four time weaker than the threshold
polymerization value
Argon Laser (514 nm) linear Polarization
500 nm
10
Results AFM images
AFM Images after irradiation
E intensity ( FDTD)
  • Two symmetric polymer lobes built up near the
    metal particles and oriented along the direction
    of polarization of the incident light
  • Polymer lobes describe the spatial distribution
    of the optical near field of the metallic
    nanoparticle excited close to its dipolar plasmon
    resonance

11
Results polarized extinction spectroscopy
Spectral degeneracy breaking of the SPR in the
hybrid nanoparticle
  • New induced symmetry C???C2?
  • Two artificial plasmon eigenmodes (508nm and
    528nm)

(a), (b) isotropic response
12
Polarized extinction spectroscopy
Dipolar diagram
?resonance(?)
Continuous tunable SPR mode ?
Quasi Continuous tunable SPR mode
13
Polarized extinction spectroscopy ? distribution
of nanoscale effective refractive index
neff(?)
Dipolar diagram
Spatial extension of the two polymer lobes
Nanoscale effective index distribution neff(?)
Reference particle surrounded by an
homogeneous medium glass substrate liquid
formulation before exposure ( nm1.5)
14
Conclusion
P
  • Controlled Nanoscale photopolymerization around a
    single metallic particles excited close to their
    dipolar plasmon resonance
  • Breaking of symmetry of the dielectric
    environment of the nanoparticles
  • Spectral degeneracy breaking of the SPR
  • Nanoscale effective index distribution
  • Tunability of the plasmon resonance
  • First step towards new hybrid metal-organic
    particles with new functionalities (polymer
    engineering)
  • Refractive index, photoluminescence (absorption),
  • Nonlinearity
  • Exciting higher SP modes
  • Multiple exposures

15
Thank you for your attention
  • Thanks to J.J. Greffet, R. Carminati and A.
    Bouhelier

16
which kind of energy conversion ? In NSOM
energy transfer between evanescent waves and the
nanoprobe ? conversion of inhomogeneous surfaces
waves into homogeneous propagating waves In our
cases near-field optical energy is locally
transferred into chemical energy ? new method of
near-field imaging new functionalities
Eeosin, Aamine
17
Case of the photo-izomerization (C. Hubert et al.
Nanoletters 5, 615)
Case of the photo-polymerization
Radical aminyle
Eeosin, AHamine
propagationtermination
18
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20
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