Precisely Controlled Fabrication of a Highly Sensitive Au Sensor Film for Surface Enhanced Spectroscopy

We propose a new method of infrared (IR) monitored two-step wet-chemical preparation of plasmonic Au nanostructures with a high degree of surface enhanced infrared absorption (SEIRA) activity. Au nanoparticles (AuNP) are deposited on SiO 2 /Si substrate and grown to form a network of densely packed islands very close to the two-dimensional percolation threshold. Monitoring the growth process with IR spectroscopy enables the termination of growth at a well defined state of the film morphology and is a great advantage compared to the previous methods. An octadecanethiol (ODT) monolayer adsorbed on the SEIRA optimized film gives a huge absorption intensity of 16.5% for the antisymmetric CH 2 stretching vibration.