Abstract

Resonantly enhanced multiphoton ionization (REMPI) affords the opportunity to select a specific ionization pathway in order to produce a particular ionic state for further study (such as state-selected ion-molecule reactions) or to investigate detailed aspects of excited-state photoionization dynamics. The production of electronic and vibrational state-selected ions has been achieved, and in some instances rotational state-selection may be possible. State-selected ions are obtained by first preparing an intermediate Rydberg state that has a potential energy curve similar to that of the desired final ionic state and then ionizing the Rydberg state with a single additional photon. Under these circumstances, the Franck-Condon factors governing the final ionization step strongly favor the preservation of the vibrational level of the Rydberg-state core. In addition, the photoionizing transition is expected to favor the further excitation of the Rydberg electron, while retaining the electronic state of the ion core. Thus REMPI through a Rydberg state having an ion core in a particular vibronic state is expected to produce ions in the same vibronic state.

© 1984 Optical Society of America