Study of Vibronic Coupling in the Tilde C State of CO sub 2+

摘要

We have studied vibronic coupling in vibrationally resolved photoionization to the fourth electronic state of CO sub 2+ , C( sup 2 sigma /sub g/ sup + ), in the photon-energy range h nu = 20 to 28.5 eV. The measurements utilize high-resolution hemispherical electron analyzers, equipped with area detectors, and the SURF-II synchrotron radiation source at the National Bureau of Standards. The angular distribution asymmetry-parameters ( beta ) for the allowed C(0,0,0) and forbidden C(1,0,1) (19.747 eV binding energy) peaks are found to be quite different. However, similarities between the C(1,0,1) beta curve and that for the B state suggest that vibronic coupling to the B( sup 2 sigma /sub u/ sup + ) state of CO sub 2+ is the explanation for the intensity of the C state forbidden band in the first 8 eV above threshold.