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Title: Effective optical constants {ital n} and {kappa} and extinction coefficient of silica aerogel

Abstract

In this work the normal reflectance, {ital R}, at a planar silica aerogel interface and the normal transmittance, {ital T}, of a silica aerogel slab were measured using a Fourier Transform Infrared Spectrometer. Two procedures were used to obtain the effective optical constants, i.e., the refractive index {ital n} and the absorption index {kappa}, of silica aerogel. One procedure determined {kappa} from the measured transmittance {ital T} and then determined {ital n} from the results for {kappa} and from the measured reflectance {ital R} using the Kramers-Kronig relation; the other procedure determined {ital n} and {kappa} of silica aerogel from {ital n} and {kappa} of fully dense silica glass by using the Clausius-Mossotti equation, Maxwell Garnett formula, and Bruggeman formula. The first procedure has a relatively large error due to the inaccuracy of the transmission and reflection measurements. The second procedure, especially the Clausius{endash}Mossotti equation, yields values of {ital n} that are consistent with experiments and may be used for the calculation of the effective optical constants and the extinction coefficient of silica aerogel. {copyright} {ital 1996 Materials Research Society.}

Authors:
;  [1]; ; ;  [2]
  1. Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States)
  2. Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory
OSTI Identifier:
279742
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Journal Article
Journal Name:
Journal of Materials Research
Additional Journal Information:
Journal Volume: 11; Journal Issue: 3; Other Information: PBD: Mar 1996
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; GELS; OPTICAL PROPERTIES; SILICA; INFRARED RADIATION; KRAMERS-KRONIG CORRELATION; TRANSMISSION; EXTINCTION

Citation Formats

Zeng, J S, Greif, R, Stevens, P, Ayers, M, and Hunt, A. Effective optical constants {ital n} and {kappa} and extinction coefficient of silica aerogel. United States: N. p., 1996. Web. doi:10.1557/JMR.1996.0083.
Zeng, J S, Greif, R, Stevens, P, Ayers, M, & Hunt, A. Effective optical constants {ital n} and {kappa} and extinction coefficient of silica aerogel. United States. https://doi.org/10.1557/JMR.1996.0083
Zeng, J S, Greif, R, Stevens, P, Ayers, M, and Hunt, A. Fri . "Effective optical constants {ital n} and {kappa} and extinction coefficient of silica aerogel". United States. https://doi.org/10.1557/JMR.1996.0083.
@article{osti_279742,
title = {Effective optical constants {ital n} and {kappa} and extinction coefficient of silica aerogel},
author = {Zeng, J S and Greif, R and Stevens, P and Ayers, M and Hunt, A},
abstractNote = {In this work the normal reflectance, {ital R}, at a planar silica aerogel interface and the normal transmittance, {ital T}, of a silica aerogel slab were measured using a Fourier Transform Infrared Spectrometer. Two procedures were used to obtain the effective optical constants, i.e., the refractive index {ital n} and the absorption index {kappa}, of silica aerogel. One procedure determined {kappa} from the measured transmittance {ital T} and then determined {ital n} from the results for {kappa} and from the measured reflectance {ital R} using the Kramers-Kronig relation; the other procedure determined {ital n} and {kappa} of silica aerogel from {ital n} and {kappa} of fully dense silica glass by using the Clausius-Mossotti equation, Maxwell Garnett formula, and Bruggeman formula. The first procedure has a relatively large error due to the inaccuracy of the transmission and reflection measurements. The second procedure, especially the Clausius{endash}Mossotti equation, yields values of {ital n} that are consistent with experiments and may be used for the calculation of the effective optical constants and the extinction coefficient of silica aerogel. {copyright} {ital 1996 Materials Research Society.}},
doi = {10.1557/JMR.1996.0083},
url = {https://www.osti.gov/biblio/279742}, journal = {Journal of Materials Research},
number = 3,
volume = 11,
place = {United States},
year = {1996},
month = {3}
}