Silica coated Au/Ag Nanorods with Tunable
Surface Plasmon Bands for Nanoplasmonics
with Single Particles
Shuang Wu,1,5 Andreas W. Schell,2 Michael Lublow,3 Julian Kaiser,1 Thomas Aichele,2
Stefan Schietinger,2 Frank Polzer,1 Sergei Kühn,4 Xuhong Guo,5 Oliver Benson,2 Matthias
Ballauff,1 Yan Lu1*
Supporting Information
Figure S1. (a) Photographs of (1) Au nanorods and (2-6) the Au-Ag core-shell nanorods with
Ag/Au molar ratios of 3:8, 3:4, 9:8, 3:2 and 9:4 within synthesis, respectively.
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Figure S2. TEM images of silica-coated Au-Ag nanorods with 5.5nm silver shell and coating
by (a) 8% TEOS resulted to 19.9nm silica and (b) 10.7% TEOS resulted to 27.5nm silica,
(Scale bars: 50nm).
Figure S3. TEM image of silica-coated Au-Ag nanorods synthesized by continuously stirring
with speed of 250 rpm, which results to inhomogeneous silica-coating.
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1.2
1.2
1.0
557nm 568nm574nm
Absorbance
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0.6
0.8
520
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600
0.4
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400
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Wavelength (nm)
Figure S4. UV-visible absorption spectra of coating Au-Ag nanorods with 5.5nm thick silver
shell (black curve) with silica by varying precursor concentrations (red curve) 8% TEOS and
(blue curve) 10.7% TEOS, respectively.
Figure S5. TEM images of silica-coated Au- Ag nanorods in aqueous solution after (a) 1 day ,
(b) 3 days and (c) in ethanol after 14 days (scale bars: 50nm).
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Figure S6. Schematic of the experimental setup: The surface topography can be mapped with
an AFM, while simultaneously DF illumination occurs from the side, incident at a flat angle,
from a fiber-coupled Xe lamp.
Abs.
1.0
0.5
0.0
400
500
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Wavelength (nm)
Figure S7. UV-vis-NIR spectra of silica coated larger Au-Ag nanorods dispersed in ethanol
solution.
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