1989 Volume 5 Issue 3 Pages 263-267
The intensity and band shape of Fourier transform infrared reflection absorption (RA) spectroscopy have been studied for the analysis of an organic thin film formed on a SiO2 substrate. The optimum experimental condition to obtain the RA spectra with the best S/N ratio was theoretically determined for perpendicular polarization at an incidence angle of 76° on the basis of Fresnel equations using a model of a three-phase system consisting of air, a thin film and an inorganic substrate. The RA spectrum calculated from the dispersions of complex refractive indexes of a thin film and a SiO2 substrate was in good agreement with the experimental spectrum. The peak intensity of the thin film was linear up to about a film thickness of 100nm under these conditions. The calculation suggested both band distortion and a peak shift in the RA spectra.
