Using a new method of constant-electric-field ionization of Rydberg states of ions, we have eliminated the influence of the direct multiphoton ionization background in multistep excitation of Yb<sup>+</sup> Rydberg states and obtained the pure spectrum of <i>np</i> (<i>n</i> = 17–86) Rydberg levels of Yb<sup>+</sup>. The precision of the value of the Yb II ionization potential has been greatly improved to 98 231.75(20) cm<sup>−1</sup>.
© 1995 Optical Society of America
W. Huang, X. Y. Xu, C. B. Xu, M. Xue, and D. Y. Chen, "Constant-electric-field ionization mass spectroscopy in laser-excited Yb+ Rydberg states," J. Opt. Soc. Am. B 12, 961-963 (1995)