THE EFFECT OF AUTOIONIZATION ON THE CO2+ X 2-PI-G VIBRATIONAL BRANCHING RATIOS IN THE WAVELENGTH RANGE 680-790 A

Vibrational branching ratios have been measured for the CO2+ X 2Πg state using photoelectron spectroscopy and monochromated synchrotron radiation. In the wavelength range encompassed by the present study the photoionization cross section is dominated by intense autoionizing resonances, most of which belong to extended Rydberg series which converse onto either the A 2Πu or the B 2Σu+ thresholds. Autoionization from these Rydberg states causes considerable variations to be observed in the vibrational branching ratios. The present data have been recorded over several members of each Rydberg series, and the results indicate that autoionization from a particular member tends to produce a vibrational distribution characteristic of the series to which that member belongs. © 1990.