J-dependence of the isotope shift in Gd I 4f 7 5d 2 6s(a 11 F)

Abstract

TheJ-dependence of the isotope shift in the terma11F of 4f7 5d2 6s between six stable Gd isotopes was found to be represented by these parameter values (in MHz):z5d(160−158)=19.4(1.8),z5d(160−157)=37.2(1.0),z5d(160−156)=42.4(1.7),z5d(160−155)=49.1(2.0),z5d(160−154)=59.0(2.0). The normalization with the corresponding changes in the mean-square nuclear charge-radiiδ〈r2〉 yields values which are almost constant, mean value:z5d/δ〈r2〉=134(14) MHZ/fm2. This indicates a second order IS interaction of the magnetic and the field shift operator.