Raman spectrum of alumina and the luminescence and absorption spectra of ruby

Abstract

Studies of the Raman spectrum of crystalline alumina are rather scanty and incomplete, evidently because of its comparative feebleness and a continuous fluorescence accompanying it. Deutschbein, who was the first to investigate the case, recorded only a single frequency shift of 415 cm^-1. Later, a second Raman line with a frequency shift of 376 cm^-1 was noticed by Miss A. Mani. A subsequent unpublished investigation by the latter gave a hint of the existence of other faint lines besides the two already reported, among which two with frequency shifts 752 cm^-1 and 633 cm^-1 appeared most definite. It seemed likely that the use of the intense λ2536.5 mercury resonance radiation as exciter would yield a much more satisfactory Raman spectrum for the substance. This hope has been realized in the present investigation. A large boule of synthetic alumina presented to Sir C. V. Raman by the Linde Air Products Co. of New York gave satisfactory results: unlike the majority of samples of synthetic alumina, this particular one did not become coloured under ultraviolet irradiation.