ABSTRACT
There are two Raman modes of A 1 g symmetry and five modes of Eg symmetry. The two A1g modes are observed at 417.4 and 644.6 cm−1, and the five Eg modes are observed at 378.7, 430.2, 448.7, 576.7, and 750 cm−1, according to Watson et al. The Raman cross-section of the 417.4-cm−1 mode has been determined to be 1.59 × 10−30 cm2/sr.unit cell or 2.00 × 10−29 cm2/unit cell. The pressure dependence of the Raman modes of sapphire has been measured by Watson et al. The temperature dependence of the Raman modes of sapphire at 379, 418, 578, 645, and 750 cm−1 has been reported by Thapa et al.
Measurements of Brillouin scattering of single-crystal sapphire at room temperature have been made by Yamaguchi. Values of the Brillouin frequency for the longitudinal and transverse phonons of sapphire at 296 K are 2.5 and 1.4 cm−1, respectively, for the laser frequency of 1.9436 × 104 cm−1. Measurements in the temperature range 300–2100 K have been made by Zouboulis and Grimsditch.
