Spectral dependence of photoexpansion in As2S3 glass

The mechanisms of photoexpansion in As(2)S(3) glass have been studied through the excitation energy dependence. When the glass is exposed to supergap light ((h) over bar omega greater than or equal to 2.7eV) in air, photodepression occurs, which is ascribable to photovaporization. In vacuum, the glass always expands. When the glass is illuminated by a weak bandgap ((h) over bar omega approximate to 2.4eV) or intense subgap ((h) over bar omega approximate to 2.0eV) light, the expansion is maximal. This intensity spectrum dependence resembles that of photoconduction, which suggests that the suppression of geminate recombination of photoexcited carriers is required for photoexpansion.