Journal of Chemical Physics, Vol.115, No.21, 9764-9770, 2001
Rotationally resolved photoionization: Influence of the 4 sigma -> k sigma shape resonance on CO+(B (2)Sigma(+)) rotational distributions
We present experimental and theoretical results on rotational distributions of CO+(B (2)Sigma (+)) photoions. Rotational distributions were determined for both the v(+)=0 and v(+)=1 vibrational levels following photoionization of cold (T(0)approximate to9 K) neutral CO target molecules. Data were generated using dispersed ionic fluorescence over a wide range of photoelectron kinetic energies, 0 less than or equal toE(k)less than or equal to 120 eV, which allows one to interrogate the ionization dynamics. This wide spectral coverage permits illustrative comparisons with theory, and calculated spectra are presented to interpret the data. In particular, the comparison between theory and experiment serves to identify the strong continuum resonant enhancement at h nu (exc)approximate to 35 eV in the l=3 partial wave of the 4 sigma-->k sigma ionization channel, as this feature has profound effects on the ion rotational distributions over a wide range of energy. Second, there are differences between the rotational substructure for the v(+)=0 and v(+)=1 vibrational levels. All of the experimentally observed features and trends are reproduced by theory, and the consequences of these comparisons are discussed.