A theoretical investigation has been made of the difference in absorbance between that calculated from the Lambert law and that from thin-layer optics which fully takes into account the effect of multiple
reflections on a symmetrical five-layer film such as black soap film. The absorbance of a black soap film can be very different from that of a thick film because of interference effects. The error involved
may be as large as 25%. In addition, for both three-layer and symmetrical five-layer films, general approximate equations are presented for the absorbance by a stratified medium due to the presence of an
absorbing layer. These equations are appropriate for film thickness on the order of 50 nm for incident radiation at 3400 cm -1 and are accurate to less than 2.5% error.
The Society publishes the internationally recognized, peer reviewed journal, Applied Spectroscopy, which is available both in print and online. Subscriptions are included with membership or can be purchased by institutional or corporate organizations. Abstracts may be viewed free of charge. Previously published as Bulletin (Society for Applied Spectroscopy)