Hydrogen influence on the optical transparency of palladium layers

The optical transparency of palladium layers within the wavelength region from 0.5 to 1.1 $\mu$m in air and in gaseous mixtures containing hydrogen in the range of 0.1 to 100 vol.% has been studied. The thermal-vacuum deposition method was used to prepare palladium layers on glass substrate. Buger's law is implemented for layers thickness of order 450 $\mathring{\mathrm{A}}$. Pd layers of more than 1200 $\mathring{\mathrm{A}}$ are damaged in 100% hydrogen medium. At some hydrogen concentration between 1–10 vol.% a sharp increase in Pd layer transparency is observed that is intrinsic for the first-order phase transition. The layer transparency change speed increases linearly with increasing the hydrogen concentration in gas medium.