Surface Plasmon Resonance

1
Surface Plasmon Resonance
General Introduction
Steffen Jockusch
07/15/07
Plasmons - collective oscillations of
the free electron gas density, often at
optical frequencies.
2
Surface Plasmon Resonance
General Introduction
Steffen Jockusch
07/15/07
Plasmons - collective oscillations of
the free electron gas density, often at
optical frequencies. Surface Plasmons -
plasmons confined to surface (interface) and
interact with light resulting in
polaritons. - propagating electron density waves
occurring at the interface between metal and
dielectric.
3
Surface Plasmon Resonance
General Introduction
Steffen Jockusch
07/15/07
Plasmons - collective oscillations of
the free electron gas density, often at
optical frequencies. Surface Plasmons -
plasmons confined to surface (interface) and
interact with light resulting in
polaritons. - propagating electron density waves
occurring at the interface between metal and
dielectric. Surface Plasmon Resonance - light
(?) in resonance with surface plasmon
oscillation
4
Requirements
2
- Material with free electrons
plasma frequency
Metals
Pb, In, Hg, Sn, Cd
UV
Cu, Ag, Au
VIS
5
Requirements
2
- Material with free electrons
plasma frequency
Metals
Pb, In, Hg, Sn, Cd
UV
Cu, Ag, Au
VIS
- Surface (interface)
flat surfaces
nanoparticles
Au
50 nm
6
Requirements
2
- Material with free electrons
plasma frequency
Metals
Pb, In, Hg, Sn, Cd
UV
Cu, Ag, Au
VIS
- Surface (interface)
flat surfaces
nanoparticles
Au
50 nm
- Light How to couple the photons to the
surface?
7
3
Total reflection on a prism
?
1
reflectance
prism
0
?c
angle
?
prism
8
4
Evanescent Wave
?
1
reflectance
prism
0
?c
angle
evanescent field
evanescent wave - nearfield standing wave,
- extends about 1/2 ?, - decays
exponentially with the distance
9
5
Surface Plasmon Resonance
?
detector
1
reflectance
Au
0
50 nm
?c
?o
angle
(Kretschmann)
10
6
Surface Plasmon Resonance Spectroscopy
?
detector
1
reflectance
Au
0
?c
angle
?o
?1
analyte
To measure - thickness changes, - density
fluctuation, - molecular adsorption
11
Surface Plasmon Resonance Spectroscopy in Sensors
7
Knoll, et.al. Biosensors Bioelectronics, 1995,
10, 903
12
8
Coupling of Light to Surface Plasmon
Prism coupler
Waveguide coupler
Grating coupler
(Kretschmann)
Homola, Chem. Rev. 2008, 108, 462
13
Nanoparticle Surface Plasmon
9
?
d ltlt
?
Nanoparticle
d
14
Nanoparticle Surface Plasmon
9
?
d ltlt
?
Nanoparticle
d
Light resonance with the surface plasmon
oscillation causes the free electrons in the
metal to oscillate.
Eustis and El-Sayed, Chem. Soc. Rev., 2006, 35,
209
15
10
Surface Plasmon-assisted Spectroscopy
Technique
Largest enhancement factor
Surface enhanced raman
1014
SERS
Nie and Emery, Science, 1997, 275, 1102.
104
Surface enhanced IR
Tsang, et.al., Phys. Rev. Lett., 1980, 45, 201.
SEIRA
104
Sum frequency generation
SESFG
Baldelli, et.al., J. Chem.Phys., 2000, 113, 5432.
104
Second harmonic generation
SESHG
Chen, et.al., Phys. Rev. Lett., 1981, 46, 145.
Surface enhanced fluorescence
100
SEF