Three key factors influencing the refractive indices of inorganic solid state materials were discussed on the basis of the concept of optical channels and the dielectric functions calculated for two series of closely related oxides. Implications of our observation concerning efficient UV blockers were discussed.

Single crystal ReS2 was characterized using atomic force microscopy (AFM) and scanning tunneling microscopy (STM). The observed atomic-resolution AFM and STM images were interpreted by calculating the total, p(r0), and partial electron density distribution, p(r0, ef), respectively, of a single ReS2 layer. The experimental and theoretical results indicate that the basal plane surface state density is dominated by contributions from the sulfur layer This is in contrast to bulk band structure calculations which would predict that the major contribution to the STM images should be from the Re atoms. Furthermore, the surface-to-tip STM images are found to be quite different from tip-to-surface images. By interpreting STM and AFM data from p(r0) and p(r0, ef) calculations, it is shown that site specific structural and electronic details of the surface can be elucidated.