PNNL

Abstract

The ionization energy of 160Gd has been determined using high-resolution laser excitation on an effusive Gd atomic beam. Even-parity J=5,6 Rydberg series were excited by three single-frequency lasers. Despite the complex electronic structure of Gd, sequences of relatively unperturbed levels were observed in teh ranges n=50-79 and 87-120. After correcting for weak perturbations, the convergence of several Rydberg series has an uncertainty of 6 x 10-4 cm-1. The final value of 49601.5142(8) cm-1 includes cumulative uncertainty in absolute laser wave numbers for the ladder of transitions coupling the Rydberg spectrum to the J=2 ground state.