Mössbauer scattering of the 166 keV gamma rays of139La
The Mössbauer scattering of the 166 keV γ-rays of139La was observed with a source of139Ce in CeO2 and scatterers of La2O3, La(OH)3, LaF3, K3LaF6, LaB6, and LaC2. The isomer shifts obtained for these compounds are compared with isomer shift data for the analogous Pr compounds. From this comparison it is inferred that the change of the mean square nuclear charge radius for the 166 keV transition is positive and of the order of 10−2 fm2.