Valence and inner-valence shell dissociative photoionization of CO in the 26–33 eV range. I. Ion-electron kinetic energy correlation and laboratory frame photoemission.

The (V_A+, V_e, e⁁) vector correlation method, combining imaging and time-of-flight resolved electron-ion coincidence techniques, is used to probe dissociative photoionization (DPI) of CO induced by vacuum ultra violet linearly or circularly polarized synchrotron radiation in the 26–33 eV photon excitation energy range. It provides original information about both the photoionization dynamics of the CO molecule and the dissociation dynamics of the CO⁺ molecular ions. The explored region corresponds to valence and inner-valence CO⁺ ionic states, which involve doubly or multiply excited electronic configurations. In this paper I we identify up to 17 DPI reaction pathways by the position of the intermediate CO⁺ molecular states in the Franck–Condon region and the (C⁺+O) or (O⁺+C) dissociation limits to which they correlate. For these processes we report the laboratory frame β_C+/O+ and β_e asymmetry parameters as well as the relative branching ratios in selected binding energy bands. The I(χ,θ_e,φ_e) molecular frame photoelectron angular distributions for selected PI processes will be reported in a companion paper II and compared with multichannel Schwinger configuration interaction ab initio calculations of these observables. [ABSTRACT FROM AUTHOR]