Sequential photon-excitation, electron-impact ionization with subsequent mass analysis has been applied to a barium atomic beam. High-resolution, Doppler-free laser excitation produces the 6s6p1P1 excited state, which is then ionized by electron bombardment. The excited state is selectively ionized when bombardment energies are between the excited- and ground-state ionization thresholds. Mass discrimination has permitted the recording of individual optical spectra for all the stable isotopes, including the 0.1% abundant 130Ba and 132Ba, in a sample with natural isotopic abundances.
© 1986 Optical Society of America
B. A. Bushaw, B. D. Cannon, G. K. Gerke, and T. J. Whitaker, "Laser-enhanced electron-impact ionization spectroscopy," Opt. Lett. 11, 422-424 (1986)