OPTICAL SPECTRA OF NaCl : Pb AND KCl : Pb Reportar como inadecuado




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Abstract : The absorption, luminescence and excitation spectra of NaCl : Pb++ and KCl : Pb++ have been determined as a function of temperature in the range 77-650 K, and concentration 80-600 ppm for NaCl and 10-500 ppm for KCl. Particular emphasis has been placed on the role of prior thermal treatments to modify the state of aggregation of the impurity, and clarify the different behaviour of NaCl and KCl. The luminescence yield in the various bands obtained by exciting in the A band has been measured as a function of temperature for both crystal systems and the role of a quenching treatment in air or in an inert atmosphere has been studied. Data are analyzed according to current views on luminescence quenching. Through the excitation spectra, evidence has been obtained that the A band is, at least, a doublet. The relative intensity of the components has been investigated as a function of temperature and prior thermal treatment. The absorption spectrum of untreated NaCl : Pb++ is particularly complex. Detailed luminescence spectra for excitation in the region around the A band, including the 265 mµ and 290 mµ bands have been obtained. The evolution of these side bands with temperature has been determined. As a consequence, strong support has been gained for the proposa1 that the 265 mµ band is due to an excitonic transition in precipitates of Cl2Pb. The band at 290 mµ consists of various overlapped bands and has to be attributed to different types of small lead aggregates.





Autor: J. Pascual F. Jaque J. Cabrera F. Agulló-López

Fuente: https://hal.archives-ouvertes.fr/



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