Abstract

The calculation of the IR absorbance of a powdered crystalline, ionic material, diluted in an appropriate IR-transparent matrix in a known proportion, is in principle possible, provided that the size and shape distributions of the particles, as well as the optical parameters of the bulk material, and those of the matrix, are known, and, in the case of the FT-IR technique, whether absolute calibration is possible, particularly at high absorbance values. In practice, a close match between observed and calculated absorbance is hindered by several factors intrinsic to the sample that are difficult to quantify, such as the degree of crystallinity of the particles and the very common clumping and aggregation of these particles, which produce a serious problem in the determination of the real filling factor of the composite sample. Some remedies to these problems are proposed in this paper and are applied to several well-known materials.

Quantitative reflectance spectra of solid powders as a function of particle size

Tanya L. Myers, Carolyn S. Brauer, Yin-Fong Su, Thomas A. Blake, Russell G. Tonkyn, Alyssa B. Ertel, Timothy J. Johnson, and Robert L. Richardson
Appl. Opt. 54(15) 4863-4875 (2015)

Effect of particle size distribution and chlorophyll content on beam attenuation spectra

J. C. Kitchen, J. R. V. Zaneveldan, and H. Pak
Appl. Opt. 21(21) 3913-3918 (1982)

Optical Scattering by Dielectric Powders of Uniform Particle Size*

J. R. DeVore and A. H. Pfund
J. Opt. Soc. Am. 37(10) 826-832 (1947)

Determination of the Optical Absorption Coefficient of Powdered Materials Whose Particle Size Distribution and Refractive Indices Are Unknown

James D. Lindberg and David G. Snyder
Appl. Opt. 12(3) 573-578 (1973)

Method for measuring mean particle size of the bulk powder using speckle patterns

Hideichi Nitta and Toshimitsu Asakura
Appl. Opt. 30(33) 4854-4858 (1991)