Additional enhancement in surface-enhanced Raman scattering due to excitation geometry

Lorenzo Rosa; Sasani Jayawardhana; Saulius Juodkazis; Paul R. Stoddart

doi:10.1117/12.915963

30 January 2012 Additional enhancement in surface-enhanced Raman scattering due to excitation geometry

Lorenzo Rosa, Sasani Jayawardhana, Saulius Juodkazis, Paul R. Stoddart

Proceedings Volume 8351, Third Asia Pacific Optical Sensors Conference; 83511T (2012) https://doi.org/10.1117/12.915963
Event: Asia Pacific Optical Sensors Conference, 2012, Sydney, Australia

Abstract

It is well known that surface-enhanced Raman scattering (SERS) substrates based on metal island films exhibit higher levels of enhancement when excited through a transparent base material than when excited directly through air. However, to our knowledge, the origin of this enhancement has never been satisfactorily explained. An initial suggestion that the additional enhancement was due to a "nearest layer effect" cannot account for the observation of additional enhancement for monolayer adsorbates. In this paper, finite difference time domain (FDTD) modelling is presented to show that the electric field intensity in between metal particles at the interface is higher for "far-side" excitation. This is reasonably consistent with the observed enhancement for silver islands on SiO2. The modelling results are in agreement with a simple physical model based on Fresnel reflection at the interface. This suggests that the additional enhancement is due to a near-field enhancement of the electric field due to the phase shift at the dielectric interface, when the light passes from the higher to the lower region of refractive index.

Citation Download Citation

Lorenzo Rosa, Sasani Jayawardhana, Saulius Juodkazis, and Paul R. Stoddart "Additional enhancement in surface-enhanced Raman scattering due to excitation geometry", Proc. SPIE 8351, Third Asia Pacific Optical Sensors Conference, 83511T (30 January 2012); https://doi.org/10.1117/12.915963

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