Spectroscopic evidence for pressure-induced metallization in solid silane*

Infrared reflectance measurements on solid silane SiH$_{4}$ have been performed under pressure up to 70 GPa at room temperature. After passing through three phase transformations, solid SiH$_{4}$ is already black at 30 GPa. At high pressures around 60 GPa, the infrared reflectance spectra exhibit a Drude metallic behavior, signaling the pressure-induced metallization in solid silane. Angle-dispersive powder x-ray diffraction studies reveal that a structural transition is accompanying the silane transition to the metallic state.