A Comparison of the Kubelka-Munk, Rozenberg, and Pitts-Giovanelli Methods of Analysis of Diffuse Reflectance for Several Model Systems

Abstract

Previous studies have shown that the Rozenberg and Pitts-Giovanelli methods are useful alternatives that may be applied to diffusely reflecting samples that fail to conform to the Kubelka-Munk theory. These studies are extended in the present work to include samples of three additional types, namely, those which incorporate the absorber in solid solution within the scattering particles, those in which the absorber is adsorbed on the surface of the scattering particles, and those consisting of a dye spotted on chromatographic papers. No single method of analysis is superior in all cases. Although the Pitts-Giovanelli method gives a much better fit in some cases, it fails to converge in others. For this reason the Kubelka-Munk and Rozenberg methods are preferred, particularly when applied to diffusers in a medium of refractive index n = 1. For such systems the Rozenberg equation reduces to a simple form that is as easy to apply as the Kubelka-Munk equation.