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 terma ¹¹ F of 4f ⁷ 5d ² 6s between six stable Gd isotopes was found to be represented by these parameter values (in MHz):z _5d (160−158)=19.4(1.8),z _5d (160−157)=37.2(1.0),z _5d (160−156)=42.4(1.7),z _5d (160−155)=49.1(2.0),z _5d (160−154)=59.0(2.0). The normalization with the corresponding changes in the mean-square nuclear charge-radiiδ〈r ²〉 yields values which are almost constant, mean value:z _5d /δ〈r ²〉=134(14) MHZ/fm². This indicates a second order IS interaction of the magnetic and the field shift operator.