FTIR study of electronic transitions in solid oxygen at high pressure and low temperature

We report near-IR measurements of the electronic (3)Sigma (-)(g) --> (1) De lta (g) (0,1) transitions of solid oxygen at high pressure and low temperat ure, Most of the P-T diagram was investigated up to the E phase by means of isothermal and isobaric scans. The electronic spectra are a powerful tool to investigate the unique properties of solid oxygen, which is a localized- spin system. Magnetism of the high pressure S phase plays a major role in d etermining the frequency of these bands, which are strongly temperature and density dependent. The analysis of this dependence allows us to model the spin correlation function and the intermolecular exchange integral.