R. Aceves et al., COEXISTENCE OF THE IMPURITY AND PERTURBED EXCITON LEVELS IN THE RELAXED EXCITED-STATE OF CSCL-PB CRYSTAL, Journal of physics. Condensed matter, 10(24), 1998, pp. 5449-5461
Four bands, all attributable to the main lead centres, have been detec
ted in the emission spectrum of CsCl:Pb crystals. Their spectral and k
inetic characteristics have been studied from 1.8 K up to 300 K, and t
he parameters of the corresponding relaxed excited states (RES) are ca
lculated. It has been shown that the new model proposed by us recently
for the RES structure of the luminescence centre in CsI:Tl is valid f
or CsCl:Pb as well. Two ultraviolet emission bands (at 4.0-3.9 eV and
3.55 eV) excited mainly in the A absorption band of pb(2+) V-c(-) cent
res (4.65 eV) are ascribed to electronic transitions from Jahn-Teller
minima of two types of the triplet RES of the Pb2+ ion. The higher-ene
rgy band is split into two components due to the presence of a cation
vacancy (V-c(-)) near pb(2+). Two visible bands (at 2.6 eV and 1.97 eV
) are connected to two different off-centre configurations of excitons
localized near the Pb2+ ion.