Pressure-Induced Molecular Dissociation and Metallization in Hydrogen-Bonded $H_{2}S$ Solid

Infrared spectra at high pressure and room temperature reveal that molecular dissociation and metallization occur in solid ${\mathrm{H}}_2\mathrm{S}$ near 46 and 96 GPa, respectively. The disappearance of SH stretching bands in the $2300–2500{\mathrm{cm}}^{-1\mathrm{}}$ region and simultaneous appearance of a lattice vibrational mode around $1300{\mathrm{cm}}^{-1\mathrm{}}$ signal the molecular dissociation. At higher pressures, a low-energy electronic absorption band develops and eventually extends throughout the infrared region studied $(700–6000{\mathrm{cm}}^{-1\mathrm{}})$. Thus, metallization seems to occur by closing a band gap originating from S-S bond formation in the dissociated phase.