Accidental predissociation phenomena in the E 1Π, v=0 and v=1 states of 12C16O and 13C16O

Abstract

We have studied v=0 and v=1 levels of the E 1Π state of CO in excitation from the ground state by one- and two-photon transitions, thus probing e and f Λ-doublet components. New accidental predissociations were found in the E 1Π, v=0 state for high J values (Je=41, 44 for 12C16O and Je=41, 50 for 13C16O). The predissociation phenomenon in the E 1Π, v=1 state at J=7 was reinvestigated and for both e and f components also J=9, 10, and 12 were found to be perturbed. Perturbations by all three spin components of a k 3Π, v=5 state were deduced. Furthermore the accidental predissociation in E 1Π, v=0 Je=31 was reinvestigated. Measurements of spectral line shifts were modeled assuming a spin-orbit coupling between E 1Π and the 3Π1 component of the k 3Π state. Relative predissociation lifetimes of k 3Π, v=3 and 5 with respect to E 1Π, v=0 and v=1 are deduced from an analysis of observed intensity effects. For the E 1Π, v=1 state rotational state dependent lifetimes were determined at low-J values. Line positions of CO lines were calibrated on an absolute frequency scale within 0.05 cm−1 against the tellurium and iodine standard in the visible. Accurate molecular constants for the E 1Π, v=0 and v=1 states are determined for both 12C16O and 13C16O. The E 1Π, v=1 state of 12C17O is observed for the first time.