Peculiarity of formation of doubly charged ions upon multiphoton ionization of barium atoms by linearly and circularly polarized radiation

Abstract

The process of formation of doubly charged ions upon multiphoton ionization of barium atoms by linearly and circularly polarized radiation of dye lasers is studied in the frequency range from 16 600 to 17 900 cm -1 . A large number of resonance maxima in the yield of Ba + and Ba 2+ ions were observed upon tuning the radiation frequency. It is unambiguously proved that most resonance maxima in the yield of Ba 2+ ions are associated with the resonance transitions in the spectrum of Ba + ions. This fact confirms the cascade mechanism of formation of Ba 2+ ions in the frequency range of localization of these maxima. But the number of the resonant maxima in Ba 2+ ions yield do not identified by transitions both in spectra of Ba atom and Ba + ion. This fact indicates on realization of the noncascade mechanism of Ba 2+ ions formation in the frequency range of these maxima.