Infrared emissions of the F center and of compound color centers in RbCl

The infrared emissions of electron color centers in single crystals of RbCl were investigated between the temperatures of 6°K and 145°K. Influences of sample purity and of center concentrations were observed. The shape of the F‐band emission was studied in detail. The emission (and absorption) peaks of the various centers at 78°K were as follows: F center 1.07 eV (2.04 eV). FA (K) center 0.95 eV (1.80 eV), M center 1.09 eV (1.43 eV), R center 0.86 eV (1.67 eV, 1.56 eV), N center (1.19 eV). Ruby laser light was used to excite the F, FA and R emissions. Photochemical changes occurred at 78°K under laser illumination creating a F3+ band which overlapped with the N band. The different ways of representing emission data of color centers are critically discussed. It is shown that the differences in the radiative lifetimes of the F centers in different alkali halides as reported by various authors only reflect the v3 dependence of the transition probability on the average frequency.