Rydberg state-mediated photoionisation of dissociating NaK wave packets inthe B-1 Pi state

The photoionisation dynamics of NaK molecules in the (BII)-I-1: state is st udied in both frequency and time domain by femtosecond laser spectroscopy. Comparison to model calculations shows that the photoionisation proceeds vi a intermediate-to-high-n Rydberg states. These Rydberg states act as Franck -Condon windows in the time-dependent experiment, and the molecular ions pr oduced by autoionisation of the Rydberg states are shown to reflect the wav e packet evolution in the B state. Consequently, Rydberg state-mediated pho toionisation is proposed as a viable method for probing molecular wave pack et dynamics. (C) 2000 Elsevier Science B.V. All rights reserved.