Narrow luminescence lines and their excitation spectra in RbI, NaI, KI and CsI crystals are studied under the excitation in the first exciton absorption band at a temperature range 5∼100 K. The most remarkable results of the luminescence are as follows: (1) This luminescence line is located quite closely to the peak position of the first exciton absorption band. (2) The half-width is smaller than 5 meV. (3) The quantum efficiencies are estimated to be 0.01, 0.001, 0.0002 and 0.0006 for RbI, NaI, KI and CsI, respectively, under an assumption that, the quantum efficiency of the total luminescence including the broad intrinsic luminescence with large Stokes shift, is to be unity. (4) Temperatures above which the intensities of these lines decrease are 20, 25, 30 and 20 K for RbI, NaI, KI and CsI, respectively. On the basis of these results, a radiative annihilation process of a free exciton is discussed.
No takes yet. Share an insight, caveat, or question.
Nishimura et al. (1977) studied this question.