Seiichi Mima

Total internal reflection Raman spectroscopy

Feasibility of total internal reflection (TIR) Raman spectroscopy as a new tool for characterizing thin surface layers has been investigated, starting with selection of the material for the internal reflection element (IRE). Sapphire was found to be the most suitable for the IRE among TiO2, SrTiO3, several kinds of flint glasses, and sapphire itself. The potential of TIR Raman method was proved by measurements on the two‐layered samples consisting of a thin surface layer of polystryene and a base layer of polyethylene. The thickness of the surface layer that could be measured by the present technique was then extensively investigated for the two‐layered samples which had the surface layer of polystryrene varying in thickness (0.006–0.93 μm) and the base layer of a constant thickness of polycarbonate (12 μm). We could measure vibrational spectra of the surface layers as thin as 0.006–0.2 μm sufficiently separately from those of the base layer. Thickness of the measurable surface layer could be varied to a ...

Total Internal Reflection Raman Spectroscopy at the Critical Angle for Raman Measurements of Thin Films

Total internal reflection Raman spectroscopy at the critical angle has been shown to be useful for Raman measurements of not only thin films but also of any samples that can be directly coated or intimately contacted on the internal reflection element (IRE). Usefulness of this technique was demonstrated for a polystyrene film (0.70 μm thick) coated on the IRE, signal enhancement being 40 as compared with the conventional normal illumination. The technique was also applied to a thin coating layer of bovine albumin on the IRE to give the spectrum of excellent signal/noise ratio.