αandβBands in Sodium Chloride

The peak energy of the $\alpha$ and $\beta$ bands in sodium chloride crystals have been measured at 77° with a vacuum ultraviolet monochromator. The $\beta$ band was well defined, and occurred at 7.40 ev with a half-width of 0.4 ev. The oscillator strength of the $\beta$ band was calculated to be 0.55. No resolved $\alpha$ band could be produced, but subtraction of absorption curves indicated that it occurred near 7.20 ev.