QUANTITATIVE ASPECTS OF FT-IR EMISSION-SPECTROSCOPY AND SIMULATION OF EMISSION-ABSORPTION SPECTRA

Recent advances in FT-IR emission spectroscopy of solids are briefly reviewed, and some neglected points concerning the measurement of blackbody radiation are dealt with. A corrected equation describing the single-beam emission spectra is given, taking into account the possible thermal radiation of the detector. Similarities between the effect of self-absorption and that of ''illegal'' data manipulations on emittance spectra are pointed out, both giving rise to spectral distortions like inverted or split peaks or altered band shapes and intensities. To avoid some of these problems, the use of a linear emission intensity scale, emissivity, is advocated, especially for quantitative work. A special case of self-absorption, namely, that of multilayer samples, is discussed, in which the spectral distributions of emitted and absorbed radiation are significantly different. Simulations of the emission-absorption spectra observed in such cases are shown to help with spectral and structural interpretation.