On the M‐Centre Luminescence in Alkali Halides. The Case of NaF and LiF

Abstract

New results concerning the M luminescence in NaF and LiF are presented. The ageing of the samples is investigated particularly in connection with MA-centre formation in NaF : Li. Trends and correlations are proposed between halfwidths, effective modes, and Huang-Rhys factors in alkali halides.

The absence of energy transfer between F and M centres in alkali halides: the case of NaF

“…In figure 1 we show an example of the emission spectra we obtained when light excitation was carried out in the M 1 band, whereas in figure 2 we show some spectra obtained by light excitation in the M F bands. It can be stressed that in the last case F-centre luminescence is present at T < 150 K. An accurate study concerning the F-centre luminescence quantum yield and lifetime has been presented previously by one of us [22]; as anticipated, the M luminescence in additively coloured NaF:Li samples was recently investigated by Bosi and Gallo [19,20]. So we were able to separate the contribution of the F-centre luminescence from that of the M centre; a deconvolution program using two Gaussian functions was adopted.…”

“…The samples we investigated are the same employed in previous experiments concerning the M-centre emission properties (see [19] and [20] to which the reader is kindly referred). Nevertheless, for the sake of clarity, we recall the following facts.…”