OPTICAL-ABSORPTION AND REFLECTION SPECTRA OF NA-((C222)NA)

The optical absorbance from 6000 to 29000 cm(-1) of vapor deposited th in films and dilute solutions of Na+(C222Na-, as well as the reflectan ce from 4000 to 25000 cm(-1) of oriented single crystals, were measure d. The major common feature is a broad band centered at approximately 15600 cm(-1) (1.94 eV). The film spectra also have a shoulder at 18900 cm(-1) (2.34 eV) and a smaller, broad peak at 24400 cm(-1) (3.03 eV) that are not present in the solution spectra. While the solution peak broadened somewhat and shifted dramatically to lower energy with an in crease in temperature, the film peak shifted only slightly because of broadening on the low-energy side, indicative of phonon assisted excit ation As expected from the anisotropic structure, the features of the reflection spectra at near-normal incidence show major differences for light polarized parallel and perpendicular to the c-axis of single cr ystals. A Kramers-Kronig analysis of the reflection spectra yields the frequency-dependent optical constants of Na+(C222Na-: the real and im aginary parts of the dielectric function, the energy loss function, th e extinction coefficient, and the absorption coefficient. Comparisons between the calculated and observed absorption spectra indicate that t he polycrystalline thin films prepared by codeposition of sodium and c ryptand[2.2.2] are partially ordered, with the c-axis perpendicular to the substrate surface.