Low-temperature single crystal reflection spectra of forsterite

The infrared reflectivities of crystalline forsterite (Mg₂SiO₄) were measured for the temperature range 295-50 K for each crystal axis, between wavenumber 5000 and 100 cm^-1. The reflection spectra show clear dependence of temperature; most of the bands become more intense, sharper and their peak positions shift to higher wavenumber with decreasing temperature. Reflection spectra were fitted with dispersion formula of damped oscillator model of the dielectric constants and the oscillator parameters in the model were derived. The absorption spectra of forsterite particle are calculated with the derived dielectric constants to show that the forsterite features are good thermal indicator for cold temperature range below 295 K.