Chemistry on Ultrafast and Ultrasmall Scales

Trevor SmithKen GhigginoPaul Mulvaney

School of Chemistry,University of Melbourne

Ultrasmall - techniques

Confocal and multiphoton microscopy

Single molecule detection and emission spectroscopy FCS, antibunching Polymers & quantum dots

Total internal reflection fluorescence (EWIF)

Ultrasmall - facilities

Scanning confocal and multiphoton microscopy Time-resolved fluorescence imaging

LaVision PicoStar TCSPC (EI, Becker & Hickl, other)

Single molecule detection and emission spectroscopy

FCS, antibunching, single molecule spectroscopy (spectrograph/CCD)

Polymers & quantum dots Total internal reflection fluorescence (EWIF) Scanning near field (SNOM)

Ultrafast - techniques

Time-correlated single photon counting Time-resolved fluorescence anisotropy

Flash photolysis Pump-probe techniques

Time-resolved absorption Fluorescence upconversion Multi-pulse, multi-wavelength photon

echoe

Ultrafast - facilities

Nanosecond flash photolysis (Nd:YAG/OPO) ns gated CCD/spectrometer

Picosecond dye lasers Femtosecond Ti:sapphire systems

oscillator/OPO system Pulse picked/cavity dumped MHz rep. rates, nJ pulse energies, tuneable

amplified femtosecond Ti:sapphire oscillator/OPA <280 kHz rep. rates, µJ-10s of nJ pulse energies,

tuneable

Facilities

Synthesis Light emitting polymers (PPVs) Quantum dots

Evanescent Waves

n1

n2

n1> n2

Standing wave

Total internal reflection(if i> c)

Evanescent waveE=Eoexp(-x/)

Refraction(if i< c)

IncidentBeam, Eo

Interface

Normal

i

EWIF spectroscopy EWIF-FCS Time-resolved EWIFS Time-resolved EWIF anisotropy Time-resolved EWIF microscopy

Expressions for polarisations perpendicular, s, & parallel, p, to plane of incidence:

In bulk solution:

In-plane:

Out-of-plane:

r t Izy t 1

2Iyy t Iyx t

Izy t Iyy t Iyx t

r t Iyy t Iyx t Iyy t Iyx t

rbulk Iyy (t) Iyx (t)Iyy (t) 2Iyx (t)

Polarised EWIF

z

x

y

TREWIF Anisotropy

0 10 20 30 40 50 60 70Time (ns)

BULK

= 64 nm

= 76 nm

= 113 nm

INCREASINGDISTANCE AWAY FROMINTERFACE

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

r(t)

N

H

S

O

3

H

“In-plane” and “Out-of-Plane” anisotropy

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 20 40 60 80 100 120

Time (ns)

r(t)

Bulk900nm353nm260nm215nm188nm155nm135nm120nm

N

N

N

H

+

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0 20 40 60 80 100 120Time (ns)

r(t)

Time-resolved EWIF microscopy

Resolution from interface ~10’s of nm