Fluorescence of Interstitial Atomic Hydrogen in Alkali Halides Doped with I−

In KCl and RbCl doped with I− interstitial atomic hydrogen shows fluorescence emission if one of the four chlorine neighbours is replaced by an I−. In KCl one emission band at 2.84 eV with a radiative decay time of 14 ns and two overlapping bands at 1.97 eV with decay times of 34 ns and 720 ns (at 4 K) are observed. Similar results are found for RbCl. The results are interpreted as due to two charge transfer type relaxed excited states, one of which is a spin quartet and responsible for the long radiative lifetime.