In this study, novel experimental total electron detachment cross sections for O2- collisions with benzene molecules are reported for the impact energy range (10-1000 eV), as measured with a transmission beam apparatus. By analysing the positively charged species produced during the collision events, relative total ionisation cross sections were derived in the incident energy range of 160-900 eV. Relative partial ionisation cross sections for fragments with m/z ≤ 78 u were also given in this energy range. We also confirmed that heavier compounds (m/z > 78 u) formed for impact energies between 550 and 800 eV. In order to further our knowledge about the collision dynamics governing the fragmentation of such heavier molecular compounds, we performed molecular dynamics calculations within the framework of the Density Functional Theory (DFT). These results demonstrated that the fragmentation of these heavier compounds strongly supports the experimental evidence of m/z = 39-42, 50, 60 (u) cations formation, which contributed to the broad local maximum in the total ionisation observed from 550 to 800 eV. This work reveals the reactivity induced by molecular anions colliding with hydrocarbons at high energies, processes that can take place in the interstellar medium under various local conditions.
Keywords: anion–molecule collisions; electron detachment cross sections; molecular dynamics; positive ion-induced fragmentation.