PHOTOMECHANICAL AND PHOTOPLASTIC EFFECTS IN SURFACE LAYERS OF CdS CRYSTALS.

An investigation was made of the influence of illumination on the microhardness of CdS crystals. Depending on the spectral composition of light, two opposite effects could be observed in a surface layer approximately 3 mu think: the photoplastic effect, manifested by an increase in the microhardness, and the photomechanical effect, resulting in its reduction. The magnitude of each of these effects increased on approach to the surface. Illumination of CdS crystals with a source producing a wide spectrum gave rise to both competing effects.