THE ELECTRONIC EXCITED STATE OF Pb++ IN KCl : IONIC REORIENTATION AND RADIATIVE LIFETIMES OF THE PHOTOSTIMULATED LUMINESCENCE

S. Benci , R. Capelletti , F. Fermi , M. Manfredi

The reorientation of ionic dipoles in their electronic ground state (e. g. s.), such as, for example, Impurity-Vacancy dipoles in alkali halides, was extensively studied. Recently reorientation was found even at very low temperatures, when I. V. dipoles have absorbed light, i. e. when they are in the electronic excited state (e. e. s.). The effect is due to the lowering of the ionic energy barrier induced by the excitation of the electronic system (diffusion model). On this basis rate equations are written in order to discuss the reorientation processes which occur in the e. e. s. of Pb++ embedded in an ordered structure of I. V. dipoles (Suzuki phase) in KCl. The reorientation efficiency in e. e. s. is thermally activated and its spectral distribution is closely related to the optical absorption spectrum. The radiative lifetimes in the temperature range 78-300 K are studied in KC1 : Pb both where, Pb++ belongs to a simple defect (I. V. dipole) and in the complex Suzuki phase. Three distinct lifetimes were found ; two of them are temperature independent while the third one increases by decreasing the temperature. The analysis of the excitation and the emission spectra of photoluminescence in KCl : Pb was performed in the range 20-300 K by using a very good resolution.

Domaines: Articles anciens

S. Benci, R. Capelletti, F. Fermi, M. Manfredi. THE ELECTRONIC EXCITED STATE OF Pb++ IN KCl : IONIC REORIENTATION AND RADIATIVE LIFETIMES OF THE PHOTOSTIMULATED LUMINESCENCE. Journal de Physique Colloques, 1976, 37 (C7), pp.C7-138-C7-144. ⟨10.1051/jphyscol:1976728⟩. ⟨jpa-00216884⟩