Tunneling recombination luminescence in KBr and KCl

The tunneling recombination luminescence bands with maxima at 550 nm in KBr and 500 nm in KCl are due to electron tunneling transitions between the ground states of F and V_k centres. The emission of σ excitons occurs as a result of electron tunneling transitions from an electron centre (presumably an F' centre) to an excited state of the (V_k + electron) system. The KBr tunnel luminescence decay data are consistent with an isolated pair model, below critical X-ray excitation doses and at temperatures ranging from 100 to 150 K.