From two excitation schemes with different intermediate states, 5d6d <sup>1</sup>P<sub>1</sub> and 5d6d <sup>3</sup>F<sub>2</sub>, the La<sup>+</sup> Rydberg series converging to La<sup>2+</sup> ground state 5d <sup>2</sup>D<sub>3/2</sub> were observed. The ionization threshold of La<sup>+</sup> was found to be 90212.8±0.5 cm<sup>−1</sup>. The autoionization Rydberg series converging to the La<sup>2+</sup> 5d <sup>2</sup>D<sub>5/2</sub> state were also obtained.
© 1999 Optical Society of America
X. P. Xie, C. B. Xu, W. Sun, P. Xue, Z. P. Zhong, W. Huang, and X. Y. Xu, "Study of La+ Rydberg and autoionization states: ionization potential of LaII," J. Opt. Soc. Am. B 16, 484-487 (1999)