M. Sakashita, H. Yamawaki, H. Fujihisa, K. Aoki, S. Sasaki, and H. Shimizu
[Phys. Rev. Lett., Vol.79, pp.1082-1085, 1997]

Infrared spectra at high pressure and room temperature reveal that molecular dissociation and metallization occur in solid H₂S near 46 and 96 GPa, respectively. The disappearance of SH stretching bands in the 2300-2500 cm^-1 region and simultaneous appearance of a lattice vibrational mode around 1300 cm^-1 signal the molecular dissociation. At higher pressures, a low-energy electronic absorption band develops and eventually extends throughout the infrared region studied (700-6000cm^-1). Thus, metallization seems to occur by closing a band gap originating from S-S bond formation in the dissociated phase.