Multiphoton ionization spectroscopy of high-lying, even-parity states in calcium

Strong ionization signals have been observed in Ca following two-photon absorption to the bound even-parity J=0 and J=2 states. Using known Ca absorption lines for calibration, 72 new states have been classified, and their energies have been determined to ± 0.1 cm-1. The new J=0 states have a constant quantum defect, whereas the J=2 states do not. © 1976 The American Physical Society.