[HTML][HTML] Near infrared surface-enhanced Raman scattering based on star-shaped gold/silver nanoparticles and hyperbolic metamaterial

CH Lai, GA Wang, TK Ling, TJ Wang, P Chiu… - Scientific reports, 2017 - nature.com
CH Lai, GA Wang, TK Ling, TJ Wang, P Chiu, YF Chou Chau, CC Huang, HP Chiang
Scientific reports, 2017nature.com
It is desirable to extend the surface-enhanced Raman scattering (SERS) from the
conventionally used visible range into the infrared region, because the fluorescence
background is lower in the long-wavelength regime. To do this, it is important to have a
SERS substrate suitable for infrared operation. In this work, we report the near infrared
SERS operation based on the substrates employing star-shaped gold/silver nanoparticles
and hyperbolic metamaterial (HMM) structure. We first fabricate the SERS substrate in which …
Abstract
It is desirable to extend the surface-enhanced Raman scattering (SERS) from the conventionally used visible range into the infrared region, because the fluorescence background is lower in the long-wavelength regime. To do this, it is important to have a SERS substrate suitable for infrared operation. In this work, we report the near infrared SERS operation based on the substrates employing star-shaped gold/silver nanoparticles and hyperbolic metamaterial (HMM) structure. We first fabricate the SERS substrate in which nanoparticles are separated from a silver film by a thin dielectric layer. Performance of the SERS substrate is investigated with a 1064-nm excitation source. Compared with similar silver film-based substrates employing respectively gold and silver spherical nanoparticles, it is found that, Raman intensity scattered by the substrate with star-shaped nanoparticles is 7.4 times stronger than that with gold nanoparticles, and 3.4 times stronger than that with silver nanoparticles. Following this, we fabricate the SERS substrate where the star-shaped nanoparticles are deposited over a HMM structure. The HMM structure comprises three pairs of germanium-silver multilayers. Further experimental result shows that, with the star-shaped nanoparticles, the HMM-based substrate yields 30% higher Raman intensity for near infrared SERS operation than the silver film-based substrate does.
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