The optogalvanic spectrum of the neutral holmium atom (Ho I) is investigated with both broadband and single-frequency cw dye lasers and a hollow-cathode lamp. Many new Ho I transitions are observed, and their possible classifications are reported. The hyperfine structure of <sup>165</sup>Ho (I = 7/2) is recorded in a number of spectral lines, and the data are analyzed to evaluate the magnetic dipole and electric quadrupole interaction constants (A and B factors, respectively) for energy levels of Ho I. The A and B constants for nine excited states, five of which belong to the 4f<sup>11</sup> 6s7p high-lying even configuration of Ho I, are reported for the first time to our knowledge.
© 1992 Optical Society of America
M. N. Reddy, S. A. Ahmad, and G. N. Rao, "Laser optogalvanic spectroscopy of holmium," J. Opt. Soc. Am. B 9, 22-26 (1992)