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Effective optical constants n and κ and extinction coefficient of silica aerogel

  • J. S. Q. Zeng (a1), R. Greif (a1), P. Stevens (a2), M. Ayers (a2) and A. Hunt (a2)...


In this work the normal reflectance, R, at a planar silica aerogel interface and the normal transmittance, 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 n and the absorption index κ, of silica aerogel. One procedure determined κ from the measured transmittance T and then determined n from the results for κ and from the measured reflectance R using the Kramers–Kronig relation; the other procedure determined n and κ of silica aerogel from n and κ 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–Mossotti equation, yields values of 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.



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Effective optical constants n and κ and extinction coefficient of silica aerogel

  • J. S. Q. Zeng (a1), R. Greif (a1), P. Stevens (a2), M. Ayers (a2) and A. Hunt (a2)...


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