ISSN:
1089-7690
Quelle:
AIP Digital Archive
Thema:
Physik
,
Chemie und Pharmazie
Notizen:
The absorption and luminescence data reported in this paper definitely confirm that the precipitates formed during high-temperature aging of Pb-doped NaCl are PbCl2 microcrystals. A detailed comparison of the optical spectra of the precipitates and free PbCl2 is presented. The absorption and luminescence spectra are essentially similar in both cases, although the splitted structure of the prominent exciton band has now been resolved for the first time in the absorption spectrum of the precipitates. The splitting has been interpreted in terms of the noncubic crystal field effect on the 3P1 excited level of Pb+2 which is considered as a cationic exciton. The gap energy Eg and the binding energy εb of the exciton have also been determined (Eg=4.86 eV, εb=0.18 eV). The same UV and blue luminescence bands, as well as a thermally induced interconversion among them, have now been observed for the precipitates as well as for free PbCl2. This luminescence behavior, not previously understood, has been explained in terms of two coexisting AT and Ax minima in the adiabatic energy surface of the 3P1 level of a Pb+2 localized exciton (Fukuda's model).
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.449859
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