Imaging the Dynamics of the Electron Ionization of CF.

The dissociation of CF following electron ionization at 100 eV has been studied using multimass velocity-map ion imaging and covariance-map imaging analysis. Single ionization events form parent CF cations in an ensemble of electronic states, which follow a multiplex of relaxation pathways to eventually dissociate into ionic and neutral fragment products. We observe CF, CF, CF, C, F, CF, CF, CF, and CF ions, all of which can reasonably be formed from singly charged parent ions. Dissociation along the C-C bond typically forms slow-moving, internally excited products, whereas C-F bond cleavage is rapid and impulsive. Dissociation from the à state of the cation preferentially forms CF and neutral F along a purely repulsive surface. No other electronic state of the ion will form this product pair at the electron energies studied in this work, nor do we observe any crossing onto this surface from higher-lying states of the parent ion. Multiply charged dissociative pathways are also explored, and we note characteristic high kinetic energy release channels due to Coulombic repulsion between charged fragments. The most abundant ion pair we observe is (CF, CF), and we also observe ion pair signals in the covariance maps associated with almost all possible C-C bond cleavage products as well as between F and each of CF, CF, CF, and C. No covariance between F and CF is observed, implying that any CF formed with F is unstable and undergoes secondary fragmentation. Dissociation of multiply charged parent ions occurs via a number of mechanisms, details of which are revealed by recoil-frame covariance-map imaging.