A New Radiochemical Method for Determining the Oscillator Strength of F Centres in Alkali Halides

Abstract

A new radiochemical method for determining the concentration of F centres in X-or y-ray coloured crystals of alkali halides is described. The method is based on the fact that

On the oscillator strength of F centers in alkali halides

“…The experimental method used for counting the F centers in alkali chlorides and bromides was described in detail in a previous paper [ 2 ] to which the reader is kindly referred.…”

“…The Co(II1) complex ions were reduced to Co2+ by the hydrated electrons e& generated from F centers upon crystal dissolution. The Go2+ ions formed were separated from the aqueous solution by solvent extraction according to the method already described [ 2 ] . The percentage of (CoA,J3+ ions reduced by e& is given by the percentage R of 6oCo activity extracted from the water solution.…”

“…Several methods were devised, but unfortunately the results obtained by the different authors (chiefly for the alkali halides NaC1, KCl, KBr) are in poor agreement with each other and apparently there is no reason for preferring one of the different values proposed [ 2 ] . Moreover, no more refined theoretical estimates off for F centers were carried out for the alkali halides mentioned above ; indeed theoretical estimates may help us in revising the different experimental methods for F-center counting.…”

“…I n Section 2 , the experimental method and the results for RbC1, due to Bosi, Fantola-Lazzarini, and Lazzarini, are presented together with the previous results [ 2 ] (for NaC1, KC1, KBr). I n Section 3, the theoretical calculations, due to Marigliano ltamaglia and Tagliacozzo are reported.…”

“…Such an estimate was proposed only for the oscillator strength of F centers in RbCl by Smith and Spinolo [3], but unfortunately no experimental determination of f was obtained for this salt. Since, recently, we have proposed a new radiochemical method for counting the F cen-L. ROSI et al ters in alkali chlorides and bromides and, as an example of its application, the oscillator strength in NaC1, KCl, and KBr was redetermined [ 2 ] , it seemed interesting to apply this method also to RbCl for purpose of comparing the experimental result with the theoretical estimate. Moreover, in order to obtain a more complete view of the problem, theoretical estimates of the oscillator strength of F centers in several alkali halides were also carried out by using the model advanced by Iadonisi and Preziosi [4].…”