Anion and cation formation following core-level photoexcitation of CO₂

Abstract

Mass-resolved anion and cation partial-yield spectra following photoexcitation of CO2 have been recorded in the vicinity of the C 1s and O 1s thresholds. Anion production was found to be site specific: a weak production of O− was observed on the π* resonance near the C K edge, whereas both C− and O− fragments were observed near the O K edge. Due to suppression of the shape resonances that dominate the cross section above the core thresholds, the anion-partial-yield spectra at the O K edge reveal several previously unobserved electronic states. In addition, several cations such as CO2+ and O2+ were observed for the first time.

Negative- and positive-ion fragmentation of core-excited formic-acid molecules studied with three- and four-ion coincidence spectroscopy

“…Above IP, the NIYs have exponential decays, attributed to postcollision interaction (PCI), where a slow photoelectron is overtaken by a fast Auger electron and subsequently recaptured when it becomes exposed to the molecule's doubly charged core. Similar behavior has been observed for several small molecules [26][27][28][29].…”

Role of the Renner-Teller effect after core hole excitation in the dissociation dynamics of carbon dioxide dication

“…Recent work highlights dissociative processes in carbon dioxide that illustrate the effects of geometry on dissociation in core-excited states, 4,5,9,13,14 ion-yield measurements identified both anions and cations produced in photoionization, 15 and fragmentation mechanisms were studied using multi-ion coincidence methods after photoexcitation, [16][17][18][19] electron impact, 20 and ion impact ionization. 3 A number of recent studies focus on triply ionized carbon dioxide 21 and its fragmentation.…”

Triple ionization of CO2 by valence and inner shell photoionization

“…6,7 Some of the doubly charged species are stable CO ++ 2 molecules, while others dissociate into singly and doubly charged fragments. [7][8][9] By contrast, the double Auger effect, in which two electrons are ejected after the photoelectron creating a triply charged nascent ion, has been less studied. No long-lived CO +++ 2 molecules are known, so only the dissociations caused by triple ionization have been examined.…”