Bound, even-parity J=0 and J=2 spectra of Sr

Abstract

Extensive new data on the even-parity, J=0 and J=2 states of Sr have been obtained using multiphoton ionization spectroscopy. Revised term values for previously observed 5s9d D21 and D23, and 5s13d to 5s16d D23 states are presented in addition to term values for newly observed S01 states up to 5s21s, D21 states up to 5s60d, and D23 states up to 5s37d. The new data clearly show an avoided crossing between the D21 and D23 series near the 5s16d levels. A strong J=2 autoionizing resonance is also observed, ∼450 cm-1 above the first ionization limit. Multichannel quantum-defect theory (MQDT) parametrizations of the S01, P1o1, D21, and D23 bound-state Rydberg series are also presented, including calculated term values for these series. The MQDT analysis of the J=2 series in Sr differs from the earlier analysis of Ca in that both configuration interactions and recoupling between D21 and D23 series must be treated simultaneously. Further, it is found that all of the major perturbations of the J=2 bound states can be reproduced without including any interactions due to a 4d2 D21, even though 3d2 D21 is a major perturber of the D21 series in Ca. © 1977 The American Physical Society.