Infrared reflection spectra of forsterite crystal

¹ Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8412, Japan e-mail: koike@mb.kyoto-phu.ac.jp
² Department of Earth and Space Science, Osaka University, Toyonaka, Osaka, Japan
³ Subaru Telescope, 650 North Aohoku Place, Hilo, Hawaii 96720, USA
⁴ Department of Earth and Planetary Science, The University of Tokyo, Japan
⁵ Division of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan

Received: 26 June 2004
Accepted: 3 January 2006

Abstract

Polarized infrared reflectance of large single crystals of forsterite was measured for each crystal axis at frequencies between 5000 cm^-1 and 100 cm^-1 with a resolution of 1 cm^-1. The reflectance spectra were analyzed based on classical dispersion theory. A set of oscillator parameters for crystalline axes of forsterite was obtained. Those parameters are used to derive optical constants of forsterite, which are important for analyses of observed spectra of astronomical objects and laboratory spectra of particle samples. Calculations of absorption for small particles using the bulk optical constants are compared with mid-infrared and far-infrared absorption spectra measured in the laboratory.