Abstract

Absorption measurements in thin films made perpendicular to the film plane are hampered by the extremely short pathlength available for typical transmission based measurements. Analytical chemists have traditionally dealt with low absorbances such as those generated in thin film media in two ways: by increasing the pathlength or by increasing the intrinsic absorption cross section of the system being measured (1). Although the latter approach works well enough in solution where some transforming chemistry may be carried out, the possibilities for rendering thin film matrices more absorbing are not abundant. Thus one must concentrate on improving the sensitivity of the measurement or increasing the optical pathlength. Another problem squarely facing accurate absorption measurements in thin films is the separation of the scattering loss from true absorption (2-4). Any transmission based measurement has this problem, however it is particularly severe when there are no readily available methods for making scattering background corrections.

© 1987 Optical Society of America