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Static and dynamic studies using Static and dynamic studies using linear reflectance and second linear reflectance and second
harmonic generation of molecular harmonic generation of molecular and metallic nanoparticles films at and metallic nanoparticles films at
the air/water interface.the air/water interface.
Gaëlle Gassin-MartinGaëlle Gassin-MartinNonlinear Optics and interfacesNonlinear Optics and interfaces
Laboratoire de Spectrométrie Ionique et Moléculaire Laboratoire de Spectrométrie Ionique et Moléculaire (LASIM) – Lyon -(LASIM) – Lyon -
General idea: Nanometric studies using nonlinear optics General idea: Nanometric studies using nonlinear optics
o Bi-dimensional films upon compressionBi-dimensional films upon compressionControl Control of the averageof the average distance distance between nano- between nano-
objects objects VaryVary the amplitude of the the amplitude of the interactionsinteractions
o Optical measurement of the electronic Optical measurement of the electronic delocalisation delocalisation Molecular systems (molecular aggregates)Molecular systems (molecular aggregates)Metallic systems (nanoparticles)Metallic systems (nanoparticles)
AimsAims
o Molecular filmMolecular filmo Langmuir film formationLangmuir film formationo Importance of optical measurement Importance of optical measurement o Properties upon compressionProperties upon compression
Polarisation resolved Second Harmonic Generation (SHG)Polarisation resolved Second Harmonic Generation (SHG)
o Metallic nanoparticles filmMetallic nanoparticles filmo Evolution of interactions upon compressionEvolution of interactions upon compression
Linear reflectanceLinear reflectance SHGSHG
o Film dynamics at the air/water interfaceFilm dynamics at the air/water interface Intensity correlation analysis Intensity correlation analysis
OverviewOverview
Molecule :Molecule : DiADiA
hydrophilic hydrophilic head head
hydrophobic hydrophobic tailtailairair
waterwater
o Amphiphilic moleculeAmphiphilic moleculeo Large nonlinear response Large nonlinear response (electrons (electrons
delocalised, « push-pull » structure) delocalised, « push-pull » structure)
Excellent surface SHG probe Excellent surface SHG probe
Molecular filmsMolecular films
Control the Control the densitydensity in situin situ
Langmuir troughLangmuir trough
barrière
film 2D
Eau Pure(sous phase)
compression
barrière
film 2Dfilm 2D
Eau Pure(sous phase)
compression
Densification
Film isothermsFilm isotherms
Knowledge of certain macroscopic states Knowledge of certain macroscopic states (S, P, T, (S, P, T, pH…pH…) ) all along the film formationall along the film formation
Control of Control of interactionsinteractions in the system in the system
30
25
20
15
10
5
0
Pre
ssio
n de
sur
face
/m
N/m
80706050403020
Surface /cm2
compressionCondensed liquidExpanded liquid
Compression
Polarisation resolved SHG of a filmPolarisation resolved SHG of a film - Experimental set up -- Experimental set up -
Experimental curves Experimental curves interpretation, exit S interpretation, exit S polarisedpolarised
70°
Langmuir trough
Mirrors
Laserfemto
Filter
Chopper Langmuir trough
Photon counter
profileprofile
AboveAbove
Analyser
Polarisation Polarisation measurement measurement
o AA wave plate permits wave plate permits the variation of the the variation of the incident light polarisationincident light polarisation
o An analyser to select the An analyser to select the emergent light emergent light polarisationpolarisation
k
S2E
E
2k
Pressure Measurement
Langmuir trough
Lens
5000
4000
3000
2000
1000
0
Inte
nsi
té S
HG
/u.a
.
440420400380360Longeur d'onde /nm
Second harmonic generationSecond harmonic generation
SHG process :SHG process : brings into brings into play play the second order the second order polarisation polarisation
SHG
2
1 2 3
1 2 30 0 0
...
: : ...
P P P P
E EE EEE
%%
22 ( ) 2( )SHGI G I %
2 nd order 2 nd order susceptibility susceptibility tensor tensor
SHGSHGmeasurementmeasurement
ExcitationExcitation at 800 nmat 800 nm
Centrosymmetric propertyCentrosymmetric property
O
X
Y
Z
M(x, y, z)
M’(-x, -y, -z) O
X
Y
Z
M(x, y, z)
M’(-x, -y, -z) E E
2 0 %%
2 2P P
2 20 :P EE
A
2 20 :P E E
A
The symmetry is very important for The symmetry is very important for this process this process
SHG is always null in SHG is always null in centrosymmetric medium centrosymmetric medium Wide interest with the surface which represents a Wide interest with the surface which represents a symmetry break symmetry break exclusive measurement of surface propertiesexclusive measurement of surface properties ( ( ) )
Centrosymmetric medium
(2)Asurf
Microscopic dimensionMicroscopic dimension
Induced dipole defined by :Induced dipole defined by :
o Hyperpolarisabilty tensor Hyperpolarisabilty tensor ββ microscopicmicroscopic parameter which parameter which characterises the molecule.characterises the molecule.
o Susceptibility tensor Susceptibility tensor χχ macroscopic macroscopic parameter which parameter which characterises the surface.characterises the surface.
polarisabilitypolarisabilityHyperpolarisabiltyHyperpolarisabilty11stst order order
0( ) . : ...t E EE %%
(2) (2)0 space
N
50
40
30
20Pre
ssio
n de
sur
face
mN
/m
2.52.01.51.00.5Densité moleculaire nmol/cm²
Surface pressure : Surface pressure : continuous growingcontinuous growing
Molecular film collapseMolecular film collapse -DiA molecular film --DiA molecular film -
o High monolayer compressionHigh monolayer compressiono Simultaneous measurements :Simultaneous measurements :
Molecular Density : 0.4 to 3 nmoles/cm²Molecular Density : 0.4 to 3 nmoles/cm²
Some information Some information remain inaccessible by remain inaccessible by
surface pressure surface pressure measurement.measurement.SHG technique SHG technique
convincingconvincing
DiA : 2 carbon chainsDiA : 2 carbon chains liquid film with a lot of defectsliquid film with a lot of defects
SHG signal falls related to SHG signal falls related to multilayer formation multilayer formation
SHG: Signal falls at SHG: Signal falls at high density high density
1200
1000
800
600
400
200
Sig
nal S
HG
/u
a
2.52.01.51.00.5Densité /nmol/cm²
(2) 0Asurf
1200
1000
800
600
400
200
Sig
nal S
HG
/u
a
2.52.01.51.00.5Densité /nmol/cm²
50
40
30
20
Pression de surface /m
N/m
(2) (2)0 N
(2) 0Asurf
centrosymmetrycentrosymmetry
Non Non centrosymmetrycentrosymmetry
Micelle
Contre-ions
Polarisation analysisPolarisation analysis -DiA molecular film - -DiA molecular film -
eeezzzeee eeezxx zyyeee eee eee eeexxz yyz xzx yzy
vC
2
1 sin 2DE eees yyzI a
400
300
200
100S
igna
l SH
G
/ua
350300250200150100500Angle de polarisation incidente /deg
Molecular Density : 0.43 nmoles/cm²Isotropic surfaceIsotropic surface
ED Approximation ED Approximation (electric dipolar)(electric dipolar)
High degree of symmetryHigh degree of symmetry
(2) eeei ijk j k
j,k
P (2 ) E ( )E ( )
incident incident polarisation anglepolarisation angle
400
300
200
100
Sig
nal S
HG
/au
350300250200150100500Angle de polarisation incidente /deg
Isotropic chiral Surface Isotropic chiral Surface -DiA molecular film - -DiA molecular film -
Molecular Density : 0.8 nmoles/cm²
Monolayer compressionMonolayer compression
2
1 sin 2DE eees yyzI a
300
200
100
0S
igna
l SH
G
/ua
350300250200150100500Angle de polarisation incidente / deg
VCisotropic surfaceisotropic surfaceED ApproximationED Approximation
eeezzzeee eeezxx zyyeee eee eee eeexxz yyz xzx yzy
Chirality with ED Chirality with ED approximation not sufficient approximation not sufficient
400
300
200
100
Sig
nal S
HG
/au
350300250200150100500Angle de polarisation incidente /deg
eee eee eee eeexyz xzy yxz yzx
C
2
1
27
sin 2
cos
eeeyyzDE
s eeeyxz
aI
a
(Chiral)(Chiral)
ChiralChiral
Unique possible origin for 90° Unique possible origin for 90° angle deformation isangle deformation is chirality's chirality's
phenomenonphenomenon
Introduction of magnetic componentsIntroduction of magnetic components -DiA molecular film - -DiA molecular film -
MD ApproximationMD Approximation
2
1 10 11
27 9
28
( )sin 2
cos
sin
eee eem eemyyz yxz yzx
DE DM eee eems yxz yzy
eemyyz
a a a
I a a
a
eem eemxyz yzxeem eemxzy yzxeem eemzxy zyx
eemzzzeem eemzxx zyyeem eemxxz yyzeem eemxzx yzy
eem eemxyz yzxeem eemxzy yzxeem eemzxy zyx
350
300
250
200
150
100
50
Sig
nal S
HG
/au
350300250200150100500Angle de polarisation incidente /deg
Molecular Density : 0.8 nmoles/cm²
Isotropic chiral SurfaceIsotropic chiral Surface
ED ApproximationED Approximation
eeezzzeee eeezxx zyyeee eee eee eeexxz yyz xzx yzy
eee eee eee eeexyz xzy yxz yzx
C
Chirality with MD Chirality with MD approximation adapted approximation adapted
(2) eee eemi ijk j k ijk j k
j,k j,k
P (2 ) E ( )E ( ) E ( )B ( )
(Chiral)(Chiral)
(Chiral)(Chiral)
Fitting curves Fitting curves Tensor elements Tensor elements which translate which translate surface state all along compression surface state all along compression
50
40
30
20
10
Pre
ssio
n d
e s
urf
ace
/m
N/m
1.21.00.80.60.4Densité /nmol/cm²
A
B
C
DE F G
70
60
50
40
30
20
10
0
Sig
nal S
HG
/
ua
350300250200150100500Densité /nmol/cm²
AA350
300
250
200
150
100
50
Sig
nal S
HG
/ua
350300250200150100500Angle de polarisation incidente /deg
BB1000
800
600
400
200
Sig
nal S
HG
/ua
350300250200150100500Angle de polarisation incidente /deg
CC1800
1600
1400
1200
1000
800
600
400
200
Sig
nal S
HG
/u
a
350300250200150100500 Angle de polarisation incidente /deg
DD1600
1400
1200
1000
800
600
400
Sig
nal S
HG
/au
350300250200150100500Angle de polarisation incidente /deg
EE2000
1500
1000
500
Sig
nal S
HG
/ua
350300250200150100500Angle de polarisation incidente /deg
FF2000
1500
1000
500
Sig
nal S
HG
/ua
350300250200150100500Angle de polarisation incidente /deg
GG
Evolution of S-polarised curves Evolution of S-polarised curves all along compressionall along compression
-DiA molecular film - -DiA molecular film -
ProgressiveProgressive symmetrysymmetry breaking breaking all all along the along the compressioncompression
Molecular Density : 0.2 to 1.4 nmoles/cm²Molecular Density : 0.2 to 1.4 nmoles/cm²threshold : 0.5 nmoles/cm²threshold : 0.5 nmoles/cm²
50
40
30
20
10
Pre
ssio
n d
e s
urf
ace
/m
N/m
1.21.00.80.60.4Densité /nmol/cm²
A B
CDE F G
2
1 10 11
27 9
28
( )sin 2
cos
sin
eee eem eemyyz yxz yzx
DE DM eee eems yxz yzy
eemyyz
a a a
I a a
a
2000
1500
1000
500
0
Signal S
HG
hH /ua
1.21.00.80.60.4Densité /nmol/cm²
-100
-50
0
50
100
/
au
Increase chiral tensor Increase chiral tensor element element Becomes comparable to Becomes comparable to
2000
1500
1000
500
Sig
nal S
HG
/ua
350300250200150100500Angle de polarisation incidente /deg
1800
1600
1400
1200
1000
800
600
400
200
Sig
nal S
HG
/ua
350300250200150100500 Angle de polarisation incidente /deg
Uncertainty about the Uncertainty about the origin origin of chiral tensor of chiral tensor evolution evolution
eeeeemyyz
Chiral tensor element Chiral tensor element -DiA molecular film- -DiA molecular film-
eemyyz
Compression
eemyyz Sign change
400
300
200
100
Sig
nal S
HG
/u
a
350300250200150100500Angle de polarisation incidente /deg
o Microscopic models of chiral aggregatesMicroscopic models of chiral aggregates
Helix aggregatesHelix aggregates
Microscopic Interpretation Microscopic Interpretation -DiA Molecular film - -DiA Molecular film -
eemyyz
Even if we lack some information we know :Even if we lack some information we know :
DiA non chiral moleculeDiA non chiral molecule
attest an isotropic chiralattest an isotropic chiral surfacesurface
ProgressiveProgressive formation formation of chiral structures of chiral structures upon compressionupon compression
Model: an electron along an helixModel: an electron along an helix
It drives us to It drives us to thinkthink about: about:
Conclusions Conclusions -DiA molecular film- -DiA molecular film-
Langmuir technique :Langmuir technique : squeeze the molecules to form a 2D squeeze the molecules to form a 2D filmfilm
Chiral aggregates formationChiral aggregates formation
SHG technique :SHG technique : sensible to surface phenomenon sensible to surface phenomenonMeasure Measure electronicelectronic delocalisation delocalisation effects in effects in
these chiral aggregates upon compressionthese chiral aggregates upon compression
Molecular FilmsMolecular Films Nanoparticles Films Nanoparticles Films
o Molecular FilmMolecular Filmo Langmuir films Langmuir films o Importance of optical measurement Importance of optical measurement o Proprieties under compressionProprieties under compression
SHG resolved in polarisationSHG resolved in polarisation
o Film of metallic nanoparticlesFilm of metallic nanoparticleso Evolution of interactions upon compressionEvolution of interactions upon compression
linear reflectancelinear reflectance SHGSHG
o Film dynamic at the air/water interfaceFilm dynamic at the air/water interface Intensity correlation analysis Intensity correlation analysis
OverviewOverview
ThioalkanesThioalkanesCC11
22
Metallic NanoparticlesMetallic Nanoparticles
Gold and Sliver Gold and Sliver Ø 7 nmØ 7 nm
Nanoparticles SynthesisNanoparticles Synthesis
hydrophobic hydrophobic particles adapted particles adapted to 2D film formation to 2D film formation
Silver Nanoparticles in chloroform
NanoParticle
Surface capped thioalkanesSurface capped thioalkanesBrustBrust
MethodMethod
Chain length variation:Chain length variation:• Chains CChains C1818 limited interactions limited interactions • Chains CChains C1212 , C , C66 … allowed interactions … allowed interactions
Collaboration LPCML ( Olivier Tillement, Stéphane Roux)Collaboration LPCML ( Olivier Tillement, Stéphane Roux)
Consequences on optical Consequences on optical response (new response (new resonances, field resonances, field enhancement…)enhancement…)
AggregatesAggregates formation formation Emergence of Emergence of interactionsinteractions
upon compressionupon compression
Nanoparticles Films Nanoparticles Films -Aims- -Aims-
Nanoparticles Nanoparticles deposit thanks deposit thanks to a microlitric to a microlitric syringesyringe
Film Film compressioncompression
LampeHaDe
Beam splitter
Objective
Langmuir trough
Detection
Langmuir Langmuir troughtrough
Pressure Pressure MeasuremeMeasureme
ntnt
Objective Objective
Beam Beam splittersplitter
Linear reflectance and SHG of a filmLinear reflectance and SHG of a film-experimental set up- -experimental set up-
Reflected Spectrum Reflected Spectrum at 90° incidence on at 90° incidence on the surfacethe surface
Sources :Sources :Linear measurements : Linear measurements : HaDe lampHaDe lamp
Metallic NanoparticlesMetallic Nanoparticlescapped Ccapped C1818
femto Laser
Filter
Filter
Dichroïc mirror
Objective
Langmuir trough
Detection
Nonlinear measurements : Nonlinear measurements : femtosecond laserfemtosecond laser
40x10-3
35
30
25
20
Réf
lect
ance
800700600500400 Longueur d'onde /nm
40x10-3
35
30
25
20
Réf
lect
ance
800700600500400 Longueur d'onde /nm
40x10-3
35
30
25
20
Réf
lect
ance
800700600500400 Longueur d'onde /nm
Surface density :Surface density : 3, 4 and 7x103, 4 and 7x101414 particles /m² particles /m²
Linear reflectanceLinear reflectance -Silver nanoparticles film- -Silver nanoparticles film-
o Strong fluctuations of Strong fluctuations of reflectance reflectance
o Disappearance of Disappearance of fluctuations for high fluctuations for high densitydensity
Reflectance is the ratio Reflectance is the ratio between reflection between reflection spectrum of the film to the spectrum of the film to the reference reflection reference reflection spectrumspectrum
2 2 consecutiveconsecutive measurements for each measurements for each compressioncompression
o Maximum reflectance Maximum reflectance Amplitude increases at Amplitude increases at 660 nm with 660 nm with compression compression
2.0
1.8
1.6
1.4
1.2
1.0
Ref
lect
ance
nor
mal
isée
800700600500400300Longueur d'onde /nm
Surface density:Surface density: 3, 4 et 7x103, 4 et 7x101414 particles /m² particles /m²
Linear reflectanceLinear reflectance -Silver nanoparticles film- -Silver nanoparticles film-
The behaviour is easily The behaviour is easily observed after observed after
normalised of the normalised of the reflectance spectra reflectance spectra
Particles in strong Particles in strong interactioninteraction equivalent to equivalent to an an ellipsoid ellipsoid (model) (model) High surface fraction High surface fraction
2.0
1.8
1.6
1.4
1.2
1.0
Réflectance theo
800700600500400Longueur d'onde /nm
2.0
1.8
1.6
1.4
1.2
1.0
Réf
lect
ance
exp
Surface density : 9x10Surface density : 9x101414 particles /m² particles /m²
Linear reflectance modellingLinear reflectance modelling -Silver nanoparticles film- -Silver nanoparticles film-
Simulations with Simulations with hypothesis of non hypothesis of non aggregated particlesaggregated particles
2.0
1.8
1.6
1.4
1.2
1.0
Réflectance theo
800700600500400Longueur d'onde /nm
2.0
1.8
1.6
1.4
1.2
1.0
Réf
lect
ance
exp
2.0
1.8
1.6
1.4
1.2
1.0
Réflectance theo
800700600500400Longueur d'onde /nm
2.0
1.8
1.6
1.4
1.2
1.0
Réf
lect
ance
exp
Simulations with Simulations with hypothesis of hypothesis of
particles particles aggregateaggregate
Isolated particles Isolated particles (weak surface (weak surface
fraction )fraction )
Effective film theory
for spherical particles
Effective filmtheory for ellipsoidal particles
50 nm22ndnd resonance shows the beginning of resonance shows the beginning of interactionsinteractions
heterogeneous set
of ellipsoid
Broaden=
ConclusionsConclusions -Silver nanoparticles film- -Silver nanoparticles film-
Strong fluctuations at weak compression which disappear at high Strong fluctuations at weak compression which disappear at high density density
Prove :Prove : Inhomogeneous Inhomogeneous surface, existence of surface, existence of domainsdomains
Domains Domains movementsmovements frozen frozen
22ndnd plasmon resonance increases plasmon resonance increases
Prove :Prove : InteractionsInteractions appear upon compression appear upon compression
Diluted system (surface filling factor = 3%)Diluted system (surface filling factor = 3%)Long alcane Chains CLong alcane Chains C1818
Expect : No aggregationExpect : No aggregation No interaction No interaction
Compression
Modification of Modification of for the particlesfor the particles
SHGSHG
A
0.4
0.3
0.2
0.1
0.0
sign
al
420410400390380longueure d'onde
Measured noise
o Continuous compressionContinuous compressiono Density: 2 to 11x10Density: 2 to 11x1014 14 particles/m²particles/m²
SHG of particles films SHG of particles films -Gold nanoparticles film--Gold nanoparticles film-
0.12
0.10
0.08
0.06
0.04
0.02
0.00
Sig
na
l SH
G
/u
a
300250200150100500
temps /s
30
25
20
15
10
5
0
pre
ssion
de
surfa
ce / m
N/m
400 nm400 nm
0.12
0.10
0.08
0.06
0.04
0.02
0.00
Sig
nal b
ruit
/u
a
300250200150100500
temps /s
30
25
20
15
10
5
0
Pre
ssion
de
surfa
ce / m
N/m
420 nm420 nm
Measured SHG
Compression
Few sharp picks
Non linear signal Non linear signal -Gold nanoparticles film- -Gold nanoparticles film-
0.12
0.10
0.08
0.06
0.04
0.02
0.00
Sig
na
l S
HG
/ua
300250200150100500
temps /s
30
25
20
15
10
5
0p
ressio
n d
e s
urfa
ce
/ mN
/m
1.0
0.8
0.6
0.4
0.2
0.0
50x10-3
40302010signal SHG /a.u.
For each average density:
o o
I
I
Log normal fitLog normal fit
Intensity histogramsIntensity histograms
6 temporal domains
35x10-3
30
25
20
15
10
5
0
Sig
nal S
HG
moy
en
/ua
3.5x1015
3.02.52.01.51.00.50.0densité moyenne de particule /m
-2
60x10-3
50
40
30
20
10La
rge
ur
de
la d
istr
ibu
tion
/u
.a.
30x10-3
2520151050
Intensité moyenne /u.a.
22 2( )SHGI G I%
(2) (2)0 N
2I N
I N
I N
Necessity to introduce the Necessity to introduce the tensor tensor . It proves the . It proves the presence of presence of interactionsinteractions between particlesbetween particles
I
I
Density variation Density variation N1N
N N
ButBut do not decrease do not decreaseI
I
I N
I N
Nonlinear signalNonlinear signal-Gold nanoparticles film--Gold nanoparticles film-
ConclusionConclusion -Silver nanoparticles film- -Silver nanoparticles film-
Necessity to introduce the element at high compression Necessity to introduce the element at high compression Prove:Prove: Existence of Existence of interactionsinteractions in compressed in compressed
filmfilm
Link with the increase of the Link with the increase of the second resonance plasmonsecond resonance plasmon concerning reflectance measurementsconcerning reflectance measurements
Recurrence of these Recurrence of these fluctuationsfluctuations phenomenon phenomenon ReflectanceReflectance SHGSHG
(2)
Diluted system (surface filling factor = 3%)Diluted system (surface filling factor = 3%)Long alkane Chains CLong alkane Chains C1818
Expect: No aggregationExpect: No aggregation No interaction No interaction
SignalSignal FluctuationsFluctuations
To extract quantitative information from this To extract quantitative information from this systematic observationsystematic observation
Analysis using autocorrelation calculationAnalysis using autocorrelation calculation
1600
1400
1200
1000
800
600
400
200
Inte
nsi
té S
HG
/u.
a.
70006000500040003000200010000Temps /s
1.8
1.7
1.6
1.5
1.4
1.3g
( t
)
0.001 0.01 0.1 1 10 100temps /s
1.8
1.7
1.6
1.5
1.4
1.3
g (
t )
0.001 0.01 0.1 1 10 100temps /s
1.8
1.7
1.6
1.5
1.4
1.3
g (
t )
0.001 0.01 0.1 1 10 100temps /s
AutocorrelationAutocorrelation functionfunction
2 distinct characteristic
times
hydrophilic silver Nanoparticles hydrophilic silver Nanoparticles Ø 7 nmØ 7 nm
SHG signal intensitySHG signal intensity
Autocorrelation calculationAutocorrelation calculation
Signal memory measurement Signal memory measurement between t et t + between t et t + 2
I t I tg
I
( ) ( )( )
Two characteristic values:Two characteristic values:
Function at the origin Function at the origin g(0)
Decorrelation characteristic Decorrelation characteristic timetime C
Reflectance fluctuation all along compressionReflectance fluctuation all along compression -Silver nanoparticles film- -Silver nanoparticles film-
140x103
120
100
80
60
40
Inte
nsité
/cps
100806040200
temps /s
Density : 1.7x1014 part/m²100x10
3
80
60
40
Inte
nsité
/cps
100806040200
temps /s
Density : 3.2x1014 part/m²100x10
3
80
60
40
Inte
nsité
/cps
100806040200
temps /s
Density : 4.4x1014 part/m²100x103
90
80
70
60
50
40
Inte
nsité
/cps
100806040200
temps /s
Density : 5.3x1014 part/m²
100x103
80
60
40
Inte
nsité
/cps
100806040200
temps /s
Density : 8x1014 part/m²
1.6
1.5
1.4
1.3
1.2
1.1
1.0
Aut
ocor
rela
tion
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
temps /s
= 1 secondc
1.6
1.5
1.4
1.3
1.2
1.1
1.0
Aut
ocor
rela
tion
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
temps /s
= 2 secondsc
1.6
1.5
1.4
1.3
1.2
1.1
1.0
Aut
ocor
rela
tion
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
temps /s
= 6 secondsc
1.6
1.5
1.4
1.3
1.2
1.1
1.0
Aut
ocor
rela
tion
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
temps /s
= 40 secondsc
1.6
1.5
1.4
1.3
1.2
1.1
1.0
Aut
ocor
rela
tion
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
temps /s
>> 100 secondsc
Characteristic fluctuation time increases Characteristic fluctuation time increases g(0) value decreasesg(0) value decreases
Signal intensitySignal intensity Autocorrelation functionAutocorrelation function
Linear signal study Linear signal study
Silver nanoparticlesSilver nanoparticlesØ 7 nmØ 7 nmcapped Ccapped C1212
1.6
1.5
1.4
1.3
1.2
1.1
1.0
g(o)
/ A
U
9080706050403020surface / cm²
autocorrelation à tau=0 eau pure autocorrelation à tau=0 film Ag
Evolution of the parameter g(0)Evolution of the parameter g(0)
g(0) decreasesg(0) decreases g(0)
Compression
Density of particles Density of particles aggregates increases aggregates increases under the laser spotunder the laser spot
1
N
g(0)
100
101
102
103
104
105
tau
/ s
9080706050403020surface / cm²
c
Evolution of the parameter Evolution of the parameter
Characteristic time Characteristic time increases increases
Compression
Frozen Frozen movementsmovements on the surface for on the surface for high density high density
Agreggate size evolution Agreggate size evolution fromfrom nmnm to to µmµm
Autocorrelation curve fittingAutocorrelation curve fitting -Silver nanoparticles film- -Silver nanoparticles film-
Autocorrelation functionAutocorrelation function2
e
D
1
1
eff dom eff
D
1 1g( ) 1 e
S 1
1.5
1.4
1.3
1.2
1.1
1.0
Aut
ocor
rela
tion
0.001 0.01 0.1 1 10 100
temps /s
Autocorrelation function from a silver nanoparticles film density 2x1014
part/m²
Spot light
Domain
vi
Brownian diffusionBrownian diffusion
Lateral flow Lateral flow
Checked : No disregard wavesChecked : No disregard waves
ConclusionsConclusions -Nanoparticles films--Nanoparticles films-
Some Some interactions between particles interactions between particles appear when the appear when the surface is compressed :surface is compressed :
Linear reflectanceLinear reflectance SHGSHG
Possibility to measure the Possibility to measure the dynamicsdynamics of the film : of the film : Presence of Presence of moving nanoparticulesmoving nanoparticules domainsdomains Dynamic evolutionDynamic evolution during compression during compression
Compression
Compression
General ConclusionsGeneral Conclusions
o Molecular films upon compression:Molecular films upon compression:Molecular Molecular aggregatesaggregates arrangement arrangement Presence of Presence of chirality chirality in aggregates in aggregates Evidence of Evidence of electronic delocalisationelectronic delocalisation in in
aggregatesaggregates
o Bi-dimensional Langmuir films studies:Bi-dimensional Langmuir films studies:Control the distanceControl the distance between nano-objects between nano-objects Modulate the interactionsModulate the interactions between nano- between nano-objectsobjects
o Metallic nanoparticles films:Metallic nanoparticles films:Beginning of Beginning of interactionsinteractions upon compression upon compression Observation of the filmObservation of the film dynamics dynamics
nano-objectsnano-objectswithout interactionwithout interaction
2D system2D systemwith interactionwith interaction
Have a look to my PhD group …Have a look to my PhD group …Thank you every Thank you every
one ! !one ! !
Pierre-François Brevet, Emmanuel Benichou, Guillaume Bachelier, Pierre-François Brevet, Emmanuel Benichou, Guillaume Bachelier, Isabelle Russier-Antoine, Christian Jonin, Isabelle Russier-Antoine, Christian Jonin,
Guillaume Revillod, Chawki Awada, Yara El Harfouch, Julien Duboisset, Lin Pu Guillaume Revillod, Chawki Awada, Yara El Harfouch, Julien Duboisset, Lin Pu