ABSOLUTE INFRARED INTENSITY MEASUREMENTS IN THIN FILMS II. SOLIDS DEPOSITED ON HALIDE $PLATES^{*}$

$^{*}$Supported by a grant from the National Science Foundation. $^{\dag}$Present address: Department of Physics. Indian Institute of Technology, Powai, Bombay 76, India. $^{1}$W. E. Person, private communication. $^{2}$D. A. Dows and G. M. Wilder, Spectrochim, Acta. 18, 1567 (1962).Author Institution: Department of Chemistry, University of Virginia“A theoretical investigation has been made of the error to be expected if reflection effects are neglected when absolute intensities are measured in thin solid films deposited on halide plates. The analysis has been applied to the experimental intensity results of Person and co-$workers^{1}$ on the antisymmetric stretching mode of $CS_{2}(s)$ deposited on AgCl, and to the intensity results of Dows and $Wieder^{2}$ on the two infrared active fundamentals of $SF_{6}(s)$ deposited on AgCl. The theoretical treatment is completely rigorous except for the fact that the vibrational absorption band is approximated by the damped oscillator model. Care has been taken to insure that the base line in the theoretical calculations corresponds to the one used experimentally. This is essential if meaningful comparisons are to be made. It is found in all three bands that the true intensity is predicted to be substantially (25-33%) than the intensity measured experimentally. Furthermore, in the case of the two $SF_{6}$ fundamental bands which are characterized by very large ratios of observed band intensity to observed band width, the shape of the experimentally observed band is influenced to a remarkable degree by reflection effects.