Raman Spectra of Selenium Dioxide at High Pressures

Raman spectra of selenium dioxide at ambient temperature and at pressures up to 10 GPa are reported. There is no evidence of any structural phase transitions in this pressure range, and only minor perturbations of the electronic states are observed. Shifts of normal mode wavenumbers with pressure are used to deduce percentage changes in the principal force constants. Interchain interactions sharply increase with pressure, whereas the stronger interchain forces show smaller increases. the Se-O bonds in side branches slightly weaken as a result of charge transfer to neighbouring bonds. the effects of pressure and temperature on the spectra are briefly compared.