Electrodynamical Analysis of Infrared Absorption Spectra Enhanced by Au Nanostructures

Abstract

We numerically analyze the spectra from the ensembles of tabular Au nanostructures at the water silicon interface which exhibit enhanced absorption effects in the infrared range. In the experiment, the water absorption signal rapidly grows and evolves into an asymmetric shape as the Au nanostructure grows and becomes connected. We used the numerical simulation based on RCWA (Rigorous coupled wave analysis) method to simulate this feature. In the simulated reflection spectrum of the O-H stretching mode at 3400cm^-1 (3μm), Fano shape appears as in the case of the experiment and we could reproduce this feature near the percolation threshold of the Au particle film.