ULTRAVIOLET SPECTRA OF ALKALI HALIDES IN INERT MATRICES

Abstract

Ultraviolet absorption spectra of several alkali halides in inert matrices have been observed in the region between 2000 and 4000 \AA. LiI, NaI, and NaBr each show one band containing several peaks. This structure probably represents transitions from the ground state to different vibrational levels of an excited electronic state of the molecules. In addition, LiI shows one broad, unstructured absorption to the red of the structured band. LiI was studied in Ar and Kr matrices, NaBr in Ar, Kr, and $N_{2}$ matrices, and NaI in Ar, Kr, Ne, and $N_{2}$ matrices. No spectra were observed for LiBr, NaCl, KI, and RbBr. The appearance of structured spectra in some of these molecules but not others can be correlated with the degree to which the molecules behave adiabatically and observe the non-crossing rule in the gas phase.