Photoacoustic Depth Profiling of Polymer Laminates by Step-Scan Fourier Transform Infrared Spectroscopy

摘要: The use of step-scan Fourier transform infrared (FT-IR) spectroscopy with photoacoustic (PA) detection for depth profiling studies polymer laminates is demonstrated. Step-scan FT-IR simplifies the extraction dept; profile information due to single modulation frequency that can be applied over entire spectral range. Because a generally used in FT-IR, thermal diffusion length, μ, constant all wavelengths scan. In addition, lock-in allows easy signal phase. Two methods are discussed and illustrated. first conventional method varying probe by changing frequency. other depends on direct phase analysis technique particularly useful cleanly separating thin (<5 μm) surface layer from bulk or substrate.