Effect of Bleaching on the Optical Band Width of the F Center in KCl

Measurements have been made of the absorption in the F region in KCl at 78^∘{}K. It has been found that the structure in this region is dependent on the presence of the M, N, R, and K bands. The broadening in the presence of small amounts of M absorption indicates that it is not simply due to the overlapping of R, M, and N bands but is caused by an additional structure. These measurements support the present interpretation of the work of Van Doorn and Haven; they can explain the difference in the measurements of Pick and Geiger as well as the difference in the half-width observed by Mollwo and more recent data.