Experimental Study of Surface Optical Modes in Ionic Crystal Slabs

Abstract
Surface optical vibrations have been revealed and investigated in slabs of a number of alkali halide crystals and crystals of CaF2 and CdF2. The measurements were carried out by the attenuated total reflection technique. The frequency dependence of reflection coefficient has been calculated in accordance with the experimental set‐up. For NaCl and CaF2 crystals dispersion curves of the surface modes have been measured at room and liquid nitrogen temperatures. The comparison of experimental and calculated data shows that the anharmonic term of the dielectric constant should be taken into account in the calculation of the surface modes.