The Isomer Shift in¹¹⁹Sn and the Quadrupole Moment of the First Excited State

Abstract

By means of the Mössbauer effect, the nuclear quadrupole splitting of the first excited state of 119Sn has been measured in several tin compounds and a comparison made of the isomer shifts of the ground state transition. The isomer shift is interpreted in terms of a change in the mean square deformation of the nucleus <β2> arising mainly from the zero-point vibrational motion. The difference in <β2> between the excited and ground states is found to be +6 × 10-4. From estimates of the field gradient at the 119Sn nucleus a value of approximately-8 × 10-26 cm2 has been assigned to the quadrupole moment of the 3/2+ state. Values of the two measured quantities are calculated using a model of a single particle coupled to a vibrator. The inclusion of pairing correlations of the nuclear force is necessary to obtain agreement with the experimental results.