A contribution to the discussion on the relaxed excited F centre

Abstract

An interpretation is given of the behaviour of the relaxed excited F centre in ternis of a hydrogenic model with broad wave functions. I n particular the dependence is considered of the lifetime T on the host crystalline matrix a t a fixed low temperature, and on the temperature T for a given matrix. Precision experimental data are given for t ( T ) in KaCI, RbCl, and KBr.On discute l'interpr6tation du comportement de 1'6tat excite relax6 du centre F par nn model hydrogenique avec des fonctions d'onde diffusbes. On considere en particulier la d6pen-dance du temps'de vie T de la matrice crystalline, t i temperature tres baisse constante, et de la temperature T dans une matrice crystalline donnee. On reporte des donnees experimentaux de haut precision pour t ( T ) en Pu'aC1, RbCl ct KBr.

Lifetime of Color Centers in NaBr

“…Nevertheless our a.nd Takiyama et al's experiments show some differences from traditional F-decay behaviour ; indeed, since a general correlation between the emission energy, E,,,, and t,he high-frequency dielectric constant, em, was found by us [ 12, 131 : and, as a direct consequence, the following relat.ionship (calculat,ed by using equation (1) of 1131) between the radiative lifetime -cK and E , is observed [13]:…”

Speculations on the absorption and emission properties of the F-centre in alkali halides

“…But this effect has been practically disregarded even if in the past one of us invoked [8] it in explaining some features of the F-centre decay, in particular the change of the lifetime value at low temperatures. More recently we confirmed [9] the validity of their [6,7] results by an accurate analysis of detailed experimental data concerning the changes in lattice parameter as a function of T.…”

To what extent are the observed lifetimes of F‐centers intrinsic?

“…Indeed, as pointed out by Fowler [27] and by us [8,91, a very small change in the wave function parameters strongly affects the lifetime value, and the decrease [9] in the effective electric field enhances its variations.…”