Understanding Coatings that Protect Plasmonic Structures for Materials Characterization and Detection and Identification of Chemical, Biological and Explosive Agents.

摘要

We have elucidated the means by which an Al2O3 protective coating prevents chemical and mechanical degradation of a silver plasmonic structure to enable Tip Enhanced Raman Spectroscopy for high resolution, high sensitivity characterization of nanostructures and detection of threats. The protective coating is very effective for measurements in air, preventing chemical degradation of the underlying silver plasmonic structure even after three months of aging. In addition, the protection is partially effective in aqueous environment. Notably, detection of different non-Raman resonant polymer isotopes at the surface was demonstrated for the first time and a new technique developed to independently measure isotopic compositions in the top monomolecular layer of a blend film using mass spectrometry. This technique we call Surface Layer-Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SL-MALDI-ToF MS).