photodissociation in an intense infrared light field

Abstract

The first experiment on infrared (IR) multiphoton excitation of with single rotational levels as initial states is reported. These states are prepared by one-photon excitation from the molecular ground state. We investigate the and ion yield, the dissociation fraction and the ion kinetic energy distribution as a function of the IR light intensity in the range from up to . The dissociation fraction depends sensitively on the initial rotational state. Transient resonances induced by AC Stark shifting states seem to influence the branching ratio between photoionization and dissociation. The photoion kinetic energy distributions show that the molecule dissociates after three-photon absorption into . The atoms are then photoionized. The AC Stark shift of the final dissociation product states in the IR light field seems to be responsible for a small intensity-dependent shift of the kinetic energy distribution.