Three‐peak Autler‐Townes splitting in the photoelectron spectrum of Li2 molecules caused by femtosecond laser pulses

Three‐peak Autler‐Townes (A‐T) splitting in the resonant multiphoton ionization photoelectron spectrum for a rotating Li₂ molecular system in femtosecond pulse laser fields is studied by using two‐dimension time‐dependent quantum wave packet method. The A‐T splitting results from rapid Rabi oscillation caused by intense femtosecond laser pulses. Because of the effects of molecular rotation and alignment, the Rabi oscillation in the population distribution will be damped in a certain degree. The three‐peak A‐T splitting can only be observed for a strongly aligned molecule with rapid Rabi oscillation. The three‐peak A‐T splitting dynamics can be affected by intensity, duration, temporal profile of laser pulse, and initial molecular rotational temperature. The conditions to observe the A‐T splitting are discussed in detail. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010