Raman spectrum of alumina and the luminescence of ruby
Using the γ 2536·5 mercury resonance radiation as exciter, the scattering of light in crystalline alumina has been investigated. The spectrum of the scattered light exhibits two Doppler-shifted components centred round the exciting line and seven Raman shifts. From the measured shift of the Doppler components the velocity of sound in alumina has been estimated. The appearance of seven Raman lines is shown to be in accord with the theoretical work of Bhagavantam and Venkatarayudu. The numerous bands appearing on both sides of the principal fluorescence doublet of ruby have been satisfactorily explained as arising from the combination of the vibration frequencies of the alumina lattice with the electronic transitions of the chromium ions.