Abstract

Autler-Townes (AT) splitting and the AC Stark shift in a molecular gas have only recently been investigated.¹ Light shifts in the two-photon excitation spectra of CO and NO were reported by Girard, et al² and by Huo, et al.³ respectively. The AC Stark shift in the (2 + 2) resonance-enhanced multiphoton ionization (REMPI) of N₂ and two-photon laser-induced fluorescence of CO was measured by Girard, et al.⁴ Using a two-color scheme Xu, et al.⁵ measured the AC Stark shift and Autler-Townes splitting in the (2 + 2) REMPI spectrum of CO. All of the above experiments utilized pulsed lasers to achieve an AT splitting or AC Stark shift large enough to overcome Doppler broadening. In our work we utilize a CW optical-optical double resonance (OODR) excitation scheme to measure the Doppler-free AT splitting and AC Stark shift in Li₂ vapor.

© 1999 Optical Society of America