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- Cl− kinetic-energy release distributions from chlorobenzene and related molecules in electron transfer experimentsPublication . Kumar, Sarvesh; Pereira, Pedro; Garcia, Gustavo; Limão-Vieira, PauloWe report a novel and comprehensive analysis of the chlorine anion (Cl−) kinetic energy release distributions (KERDs) from electron transfer experiments at 12, 40 and 118 eV collision energies in the centre-of-mass frame. These distributions have been obtained from the shape and width of Cl− time-offlight mass spectra from collisions of neutral potassium (K) atoms with a set of selected neutral chlorinated compounds, viz. C6H5Cl, C6D5Cl, C6H11Cl and C6Cl6. The reactions producing bond breaking of the temporary negative ions formed with an excess of internal energy in such collisions, are a result of intramolecular energy redistribution through the different available degrees of freedom due to statistical degradation via vibrational excitation and partly due to direct transformation into translational energy of the fragment anions. The Cl− low-energy kinetic energy release, εd, has been fitted with a statistical function and the role of the different available resonances in the collision dynamics has been discussed, allowing therefore to obtain relevant information on the electronic structure involved in negative ion formation. From Cl− kinetic-energy release maxima as a function of the collision energy, C6Cl6 shows the lowest values which have been attributed to the strong competition with the parent anion formation. In contrast, C6H11Cl shows the highest values which result from this molecular system having no π delocalized electrons over the ring, and the electronic state spectroscopy is mostly dictated by relevant σ* antibonding character along the C–Cl coordinate.
- Combined experimental and theoretical studies on electron transfer in potassium collisions with CCl4Publication . Regeta, K.; Kumar, S.; Cunha, T.; Mendes, Mónica; Lozano Martínez, Ana Isabel; Pereira, Pedro; Garcia, G.; Moutinho, A. M. C.; Bacchus-Montabonel, Marie-Christine; LIMAO-VIEIRA, PNegative ion formation in electron transfer experiments from fast neutral potassium (K) atom collisions with neutral tetrachloromethane (CCl4) molecules has been investigated in the laboratory frame range of 8-1000 eV. Comprehensive calculations on the electronic structure were performed for CCl4 in the presence of a potassium atom and used to help analyze the lowest unoccupied molecular orbitals participating in the collision process. Additionally, K+ energy loss produced in the forward direction has served to further our knowledge on the electronic state spectroscopy of CCl4. A vertical electron affinity of -0.79 +/- 0.20 eV has been obtained and assigned to a purely repulsive transition from CCl4 ground state to the(2)T(2) state of the temporary negative ion yielding Cl- formation. Other features in the energy loss spectrum were observed for the first time and related to Cl-2(-), CCl2-, and CCl3- formation. Special attention is also given to the unresolved feature corresponding to a positive electron affinity of 0.24 +/- 0.2 eV, assigned to a vibrationally hot transition from CCl4 ground state into the triply degenerate T-2(2) excited state of the negative ion. The combined time-of-flight mass spectrometry together with K+ energy loss data represents the most comprehensive assignment of the tetrachloromethane anion yields and the role of CCl4 electronic states in collision induced dissociation to date.