The Influence of Hydrogen on the Optical Transparency of Palladium Layers

The optical transparency of palladium layers is studied in the wavelength range of 0.5–1.1 μm in air and gas mixtures containing hydrogen in concentrations from 0.1 to 100 vol %. The layers were deposited on glass substrates by thermal evaporation in vacuum. The Bouguer law is fulfilled for layers with thicknesses of the order of 450 A. The layers with thicknesses exceeding 1200 A disintegrate in 100% hydrogen. An abrupt increase in the transparency of palladium layers typical for first-order phase transitions was observed at a hydrogen concentration between 1 and 10%. The rate of the hydrogen-induced change in the transparency of layers linearly increases with increasing hydrogen concentration in the gas mixture.