POLARIZATION EFFECTS IN MOLECULAR MULTIPHOTON IONIZATION SPECTROSCOPY
Ohio State University
The polarisation dependence of two-photon resonant, three-photon ionization of gas phase polyatomic molecules has been investigated. Under most experimental conditions, the multiphoton ionization has a polarisation dependence which is identical to that of the two-photon resonance alone. This can be established from either a perturbation or rate equation treatment of the multiphoton process. The symmetry of the two-photon state can thus be assigned by measuring the ratio of ion current from a circularly polarized to a linearly polarised laser. After this procedure is experimentally verified for several molecules with two-photon states of known symmetry, it will be used to assign forbidden states in hexatriene, pyridine, and pyrazine.
Author Institution: Department of Chemistry,, University of California,