Raman spectrum of diamond

Abstract

The new approach to the dynamics of crystal lattices made by Sir C. V. Raman leads in the case of diamond to the result that the atomic vibration spectrum of this crystal should exhibit eight distinct monochromatic frequencies. Of these, the highest frequency (1,332 cm^-1 in spectroscopic units) corresponds to the triply degenerate vibration of the two Bravais lattices of the carbon atoms with respect to each other, this being active in the Raman effect. The other seven frequencies represent oscillations of the layers of carbon atoms parallel to the faces of the octahedron or the cube occurring normal or tangential to these planes with the phase reversed at each successive equivalent layer. All the seven modes of vibration of this description are inactive in the Raman effect as fundamentals. The octaves of these frequencies may however, appear as frequency shifts in the Raman spectrum, though with intensities extremely small compared with that of the Raman line of frequency shift 1,332 cm^-2. Besides the octaves, various combinations of these frequencies may also appear in the Raman spectrum.