The high frequency Raman bands of vitreous SiO2

We have investigated the high frequency (1000–1300 cm−1) Raman spectroscopy envelope of vitreous silica (SiO2). The purpose of the study is to elucidate the multicomponent nature of the two bands in the high frequency envelope of v-SiO2. This is important as inferences about the nature of silicate glasses are often made based on fi􀀬ing of these and other Raman bands. The high frequency envelope has two broad bands at 1065 and 1200 cm−1. These bands are commonly assigned to the T2 and A1 motions of an isolated SiO2 tetrahedron. However, we show that both broad bands are composite peaks each consisting of two individual peaks at 1054 and 1090 cm−1 (1065 cm−1), and 1181 and 1235 cm−1 (1200 cm−1), respectively. Furthermore, the assignment of the higher frequency band to an A1 symmetric stretch is unlikely given that polarised spectra indicate that the bands in the 1200 cm−1 envelope are highly depolarised.