Three-step laser excitation was used to populate and observe members of Rydberg series in neutral iron with high effective quantum numbers. These series converge to the ground and to the first excited state of singly ionized iron The photoionization threshold was also observed. Analyses of the Rydberg series yield the value 63 737(1) cm−1 or 7.9024(1) eV as the ionization potential of neutral iron.
© 1984 Optical Society of America
E. F. Worden, B. Comaskey, J. Densberger, J. Christensen, T. M. McAfee, T. A. Paisner, and J. G. Conway, "The ionization potential of neutral iron, Fe I, by multistep laser spectroscopy," J. Opt. Soc. Am. B 1, 314-316 (1984)