1. J. Houghton and S. D. Smith, Infrared Physics, Oxford Univ. Press, Oxford, 1966.
2. The nomenclature and symbols used are those recommended by the International Union of Pure and Applied Chemistry (I.U. P.A.C.) [in ‘Manual of Symbols and Terminology for Physicochemical Quantities and Units’ (1979), I.U.P.A.C., Oxford, and Pure and Applied Chemistry, (1979)], and the In-ternational Union of Pure and Applied Physics, (I.U.P.A.P.), [in document U.I.P. 20, ‘Symbols, Units and Nomenclature in Physics’ (1978) and Physica, 93A, 1 (1978)].
3. E. Steger and R. Rasmus, Appl. Spectrosc., 28, 376 (1974).
4. D. Kember and N. Sheppard, Appl. Spectrosc., 29, 496 (1975).
5. J. E. Blanke, S. E. Vincent, and J. Overend, Spectrochim. Acta, 32A, 163 (1976).