Moessbauer effect observation of divalent gadolinium

Rhurne.- L'absorption resonnante des rayons y de 86,s keV de lssGd a kt6 utilisk pour dktec-ter le gadolinium divalent dans CaF2: Gd. Le deplacement isomerique mesure entre Gd2+ et Gd3+ est-k (0,35 $: 0,09) mm s- 1, ce qui confirme la structure electronique 4f7 5dl de Gd2+. On deduit la valeur A < r *> =- (8,2-f 2,l) x 10-3 fm2 pour la transition de 86,5 keV. Les klatements mesures pour le gadolinium dans 1'Ctat divalent sont beaucoup plus eleves que pour le gadolinium trivalent. Abstract.- Resonant absorption of the 86.5 keV gamma rays from 1sSGd has been used to detect divalent gadolinium in CaF2: Gd. The isomer shift between GdZ+ and Gd3+ was measured to be 4- (0.35 f 0.09) mm s-1 confirming that the electron configuration of Gd2+ is 4f7 5dl. The value of A < r2> for the 86.5 keV transition was deduced to be- (8.2 f 2.1) x 10-3 fm2. The measured splittings for gadolinium in the divalent state were found to beconsiderably larger than for trivalent gadolinium. 1. Introduction.- The