Vibrational Spectra of Ruby and Haematite in the Infrared Region

The reflection and transmission spectra of ruby, pure α–Al 2 O 3 and haematite (α–Fe 2 O 3 ) were observed in the infrared region from 2 to 200 µ. Six bands were found for each compound in accordance with the conclusion of factor group analysis, which predicts two bands polarized parallel to the c -axis and four bands perpendicular to the c -axis. By examining the reflection spectrum with a polyethylene sheet polarizer, the polarization character of some of the bands beyond 17.5 µ was confirmed; but complete assignment of the six bands was not tried because of the insufficiency of the polarization data under 17.5 µ for ruby, and due to unfavorable orientation of the crystal surface for haematite.