Excitation of surface plasmons with a scanning tunneling microscope

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Excitation of surface plasmons with a scanning
tunneling microscope Tao Wang, Elizabeth
Boer-Duchemin, Yang Zhang, Geneviève Comtet,
Gérald Dujardin ISMO, ORSAY Projet ANR/PNANO
 Nanosources de photons 
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Surface Plasmon Polariton
Surface plasmon polariton (SPP) EM wave
confined at Metal-dielectric interface, coupled
with oscillation of surface charges
D
z
x
M
kspp gt k0
?SPP lt?0, Beat the diffraction limit !
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Motivation
Our experiment surface plasmon excitation with a
scanning tunneling microscope
Surface plasmon excitation usually with light
laser
k0
STM tip
Kspp
Kspp
Kspp
Kspp
e-
Our experiment is to do local electrical
excitation of surface plasmons on a gold film by
STM as a nanosource of photons.
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Experiment setup
STM head
Inverted optical microscope
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Experiments
Experiment 1 thin gold film (35nm) Experiment
2 thin gold film (35nm) with gold
nanoparticles(NPs) Experiment 3 thick gold
film (200nm) with holes
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Experiment 1 STM excited on thin gold film
(35nm) Image plane image with oil objective
oil objective 100X, NA1.45 W tip, 2.5V, 6nA
Image plane
Surface plasmon propagates on the gold film
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Gold films deposition in IEF CTU, Orsay
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Experiment 1 STM excited on thin gold film
(35nm) Fourier plane
f
f
Fourier plane
Rnsin (?)f
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Experiment 1 STM excited on thin gold film
(35nm) Fourier plane images with oil objective
oil objective 100X, NA1.45 W tip, 2.5V, 6nA
kspp
nk0
?spp
R
Surface plasmons emit at large angles (related to
leakage radiation coupling)
Fourier plane
Coupling condition ksppnk0 sin(?spp)
ksppk0, sin(?spp)kspp/nk01/n,
?sppcritical angle
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Experiment 1 STM excited on thin gold film
(35nm) Spectra measurement
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Experiment 1 STM excited on thin gold film
(35nm) Conclusion
STM can excite propagating surface plasmon on the
gold film (broad spectra band)
Propagating surface plasmons emit at large angles
This will be published on nanotechnology soon.
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Experiment 2 thin Au film (35nm) with Au
NPs STM topography image (9µm9µm)
500nm
Tip position
Collaboration with Prof. Hynd Remita (LCP, Orsay)
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Experiment 2 thin Au film (35nm) with Au
NPs Preliminary results
image plane image 9µm9µm
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Experiment 2 thin Au film (35nm) with Au
NPs Preliminary conclusion
STM excite propagating surface plasmon on the
gold film
Propagating surface plasmon scattered by the Au
NPs
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Experiment 3 thick gold film (200nm) with
nanoholes STM Topography image (6µm6µm)
3µm
Collaboration with Serge Huant (Néel, Grenoble)
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Experiment 3 thick gold film (200nm) with
nanoholes Preliminary results
STM excited light emission image
5µm
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Experiment 3 thick gold film (200nm) with
nanoholes Preliminary conclusion
STM excite propagating surface plasmon on the
gold film
Propagating surface plasmon scattered by the
nanoholes
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Conclusions and future work
Experiment 1 thin gold film (35nm) Experiment
2 thin gold film (35nm) with gold
nanoparticles(NPs) Experiment 3 thick gold
film (200nm) with holes
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• Thank you for your attention!

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