QUANTITATIVE-ANALYSIS OF POWDER MIXTURES BY DIFFUSE REFLECTANCE

Previous tests of continuum diffuse reflectance models are extended in the current study to include powder mixtures in which one component is an intense absorbant and the other is a nonabsorbing scatterer. For model systems of this type, the Pitts-Giovanelli formula gives a very good fit over a large concentration range. However, the fitting procedure is very sensitive to the initial estimate of parameters, and it failed to converge in several cases. The Rozenberg formula, on the other hand, was very stable and gave a moderately good fit to the data, particularly for low reflectances. A simplified version of the Rozenberg formula, R//o/R equals 1 plus beta , was almost as good, and represents a very simple formula which should be quite useful for quantitative analyses.