INVESTIGATION OF THE SURFACE-LAYER OF POLISHED KCL AND NACL-CRYSTALS

The surface and near-surface layers of the polished optical surfaces of crystals are investigated by optical methods. It is shown that the use of multiangle ellipsometry makes it possible to estimate the depth of the damaged layer and the fluctuations of the refractive index in it. Multiple FTIR measurements have made it possible to establish that the principal type of contaminants in the near-surface layer are hydroxyl anions and water molecules, adsorbed from the surrounding atmosphere. It is shown that high-temperature annealing makes it possible to reduce the depth of the damaged layer and to passivate the crystal surface with respect to the adsorption of water from the atmosphere.