gaëlle gassin-martin

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


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


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


Chirality with ED Chirality with ED approximation not sufficient approximation not sufficient

400

300

200

100

Sig

nal S

HG

/au


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


Molecular Density : 0.8 nmoles/cm²

Isotropic chiral SurfaceIsotropic chiral Surface

ED ApproximationED Approximation


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


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


BB1000

800

600

400

200

Sig

nal S

HG

/ua


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


EE2000

1500

1000

500

Sig

nal S

HG

/ua


FF2000

1500

1000

500

Sig

nal S

HG

/ua


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


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


-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


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


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


40x10-3

35

30

25

20

Réf

lect

ance


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


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


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


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


3

80

60

40

Inte

nsité

/cps

100806040200

temps /s


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

gaëlle gassin-martin

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