Behaviour of the lowest excited triplet state of a divalent lead ion. From an isolated impurity to an exciton

Absorption and luminescence of divalent lead both as an impurity and as a cation in lead chlorides are obtained. The observed trend in emission spectra is discussed taking into account the very low local symmetry in all measured lead compounds. The luminescence spectral shift in the series of the measured lead chlorides is ascribed to the larger local distortion in relaxed excited state in some structures.