ABSTRACT
Raman scattering is inelastic light scattering by optical phonons in crystals. Raman scattering was discovered by C. V. Raman in 1928. Diamond possesses one triply degenerate zone-center optical phonon, which occurs at 1331.9 cm−1 at room temperature, as reported by Bhagavantam. The temperature variation of the Raman frequency of diamond was determined by Nayar for the temperature range 85–1130 K. The Raman frequency of diamond decreases from 1334 cm−1 at 85 K to 1316 cm−1 at 1130 K. Polarization features of the first-order Raman line have been measured by Solin and Ramdas. The Raman cross-section for 785-nm excitation of diamond has been determined to be 2.7 ± 0.6 × 10−29 cm2 per carbon atom by Aggarwal et al. Experimental results of Solin and Ramdas for the room-temperature second-order Raman scattering in diamond have been compared with the calculated results of inelastic neutron scattering by Dolling and Cowley.
Brillouin scattering in crystals is inelastic scattering of light by acoustic phonons. The values of the Brillouin frequencies are 4.1 and 3.0 cm−1, respectively, for the longitudinal and transverse phonons using the values of 2.45 for the refractive index, 6.15 × 1014 Hz for the excitation laser frequency, and 90° for the scattering angle.
