Isomerieverschiebungen der 81 keV γ-Linie des¹³³Cs

Abstract

Isomer shifts of the 81.0 keVγ-transition in¹³³Cs have been measured by the Mössbauer technique for eight ionic Cs compounds, and for the intermetallic compound CsBi₂. The source was¹³³Ba in CaF₂. The shifts, relative to CsCl, range from −1.4 · 10⁻⁸ eV for CsNO₃ to +1.6 · 10⁻⁸ eV for CsBi₂. The difference in electron density at the Cs nucleus between CsBi₂ and CsNO₃ is discussed using chemical bonding arguments. For the Cs halides, this difference is estimated from the overlap of outer electron shells in the lattices. A relative change of the mean square charge radiusδ〈r ²〉/〈r ²〉=+2 · 10⁻⁴ is derived.