Electronic states of the O 3+ radical cation

Abstract

Highly correlated MRCI wavefunctions have been used to calculate the symmetry ordering of the doublet and quartet states in the Franck-Condon region of the photoelectron spectrum of ozone. In addition, parts of the potential energy functions of the four lowest doublet states of O 3 + have been mapped by ab initio valence CASSCF calculations. The results allow an unambiguous symmetry assignment of the photoelectron spectrum of ozone in the region from 12.5 to 14 eV. The almost degenerate two lowest electronic states (X 2A 1 and A 2B 2) form a conical intersection in the Franck-Condon region for the photoionization of ozone and are coupled by the antisymmetric stretching mode. Photofragmentation of O 3 + by visible light results from transitions reaching conical intersections between the 2A 2 and 2B 1 states. Regions are found where Renner-Teller and Jahn-Teller coupling exist.