SERS optimization of gold nanocylinder arrays: Influence of the surrounding medium and application for Polycyclic Aromatic Hydrocarbons detection

摘要

The investigation is done with liquid media gradually approaching the marine media compositions. Different compounds from probe molecule like trans-1,2-bis(4-pyridyl) ethylene (BPE) to Polycyclic Aromatic Hydrocarbons ( (PAHs) such as naphthalene are investigated. Their SERS intensities obtained from characteristic vibration bands are optimized as function of the surrounding medium in which they are immersed. The best SERS intensities are obtained by the optimization of nanolithographied substrates by choosing the appropriate gold nanoparticles size. We will notably show that the optimum nanocylinder size is shifted to lower diameter by increasing the dielectric constant of the liquid medium. This rule will be discussed in term of Localized Surface Plasmon Resonance since its position influences directly SERS intensity.This study is done for two excitation wavelengths, 632.8 nm and 785 nm, permitting the comparison of SERS substrates behaviour in both cases. The aim of this work is to collect some key information in order to product future active SERS sensors suitable for in situ environmental analysis.