Measurement of the Optical Constants of Sand Samples Using Ellipsometry on Sand-Adhesive Composites.

Autor:	Frantz JA; Optical Sciences Division, U.S. Naval Research Laboratory, Washington, District of Columbia, USA., Hart MB; Optical Sciences Division, U.S. Naval Research Laboratory, Washington, District of Columbia, USA., McGinnis CL; Optical Sciences Division, U.S. Naval Research Laboratory, Washington, District of Columbia, USA., Myers JD; Optical Sciences Division, U.S. Naval Research Laboratory, Washington, District of Columbia, USA., Ewing KJ; Optical Sciences Division, U.S. Naval Research Laboratory, Washington, District of Columbia, USA., Selby JB; U.S. Navy, Washington, District of Columbia, USA., Major KJ; Institute for Functional Materials and Devices, Lehigh University, Bethlehem, Pennsylvania, USA., Watnik AT; Optical Sciences Division, U.S. Naval Research Laboratory, Washington, District of Columbia, USA., Sanghera JS; Optical Sciences Division, U.S. Naval Research Laboratory, Washington, District of Columbia, USA.
Jazyk:	angličtina
Zdroj:	Applied spectroscopy [Appl Spectrosc] 2024 Apr; Vol. 78 (4), pp. 403-411. Date of Electronic Publication: 2024 Feb 22.
DOI:	10.1177/00037028241231296
Abstrakt:	In order to model the propagation of light through a sand cloud, it is critical to have accurate data for the optical constants of the sand particles that comprise it. The same holds true for modeling propagation through particles of any type suspended in a medium. Few methods exist, however, to measure these quantities with high accuracy. In this paper, a characterization method based on spectroscopic ellipsometry (SE) that can be applied to a particulate material is presented. In this method, a polished disc of an adhesive compound is prepared, and its optical constants are measured. Next, a mixture of the adhesive and a sand sample is prepared and processed into a polished disc, and SE is performed. By treating the mixture as a Bruggeman effective medium, the optical constants of the particulate material are extracted. For verification of the proposed method, it is first applied to pure silica powder, demonstrating good agreement between measured optical constants and literature values. It is then applied to Arizona road dust, a standard reference material, as well as real desert sand samples. The resulting optical constant data is input into a rigorous scattering model to predict extinction coefficients for various types of sand. Modeling results are compared to spectroscopic measurements on static sand samples, demonstrating good agreement between predicted and measured spectral properties including the presence of a Christiansen feature near a wavelength of 8 µm. Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Databáze:	MEDLINE
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