Phase-Resolved Depth Profiling of Thin-Layered Plasma Polymer Films by Step-Scan Fourier Transform Infrared Photoacoustic Spectroscopy

Abstract

After reviewing the background of step-scan interferometric photoacoustic spectroscopy, this paper describes a step-scan Fourier transform photoacoustic phase-resolved technique and its applications in depth profiling of micrometer -thick layered plasma polymers. In particular, the power of direct use of the photoacoustic phase spectrum in both qualitative and quantitative depth profiling of the layered samples is extensively discussed. The effects of both spatial origin and intensity of a photoacoustic signal on its phase have been explicitly analyzed for both overlapping and distinctive, nonoverlapping, bands of the thin-layered plasma polymer samples. The phase spectrum technique is shown to be a very effective and efficient method of spectral depth profiling analysis.