| Autor: |
Wolff W; Physics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil., Perlin A; Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil., Oliveira RR; Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil., Fantuzzi F; Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany., Coutinho LH; Physics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil., de A Ribeiro F; Federal Institute of Rio de Janeiro, Nilópolis, RJ 26530-060, Brazil., Hilgers G; Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany. |
| Abstrakt: |
In this work, we report a systematic search of metastable C 6 H n 2+ ( n = 1-6) dications from electron impact time-of-flight measurements of several benzene derivatives in combination with global minimum search based on the genetic algorithm. Our theoretical calculations reveal that the C 6 H n 2+ ( n < 6) global minimum structures are completely different from that of the benzene dication, featuring linear carbon chains and/or cyclopropenylium moieties. Experimentally, the doubly charged species were investigated for a wide range of electron impact energies, from 20 to 2000 eV, for benzene and several monosubstituted compounds containing either electron-withdrawing or -donating groups. Furthermore, the C 6 H n 2+ production, evaluated from the yields of the dications with respect to that of the parent ion (or parent dication), was compared to those obtained from charge exchange in the doubly charged 2E spectra and electron impact experiments available in the literature. The yields of the long-lived benzene dications were contrasted to those analogues formed in chlorobenzene. Moreover, the formation of C 6 H n 2+ species is strongly dependent on the nature of substituent groups, with electron-withdrawing ones favoring the dication formation. |
