Fragmentation of multiply charged hydrocarbon molecules C{sub n}H{sup q+} (n{<=} 4, q{<=} 9) produced in high-velocity collisions: Branching ratios and kinetic energy release of the H{sup +} fragment
- Institut des Sciences Moleculaires d'Orsay (ISMO), UMR CNRS 8214, Universite Paris Sud 11, bat.210, F-91405 Orsay Cedex (France)
- Laboratoire de Chimie Physique (LCP), UMR CNRS 8000, Universite Paris Sud 11, Bat.349, F-91405 Orsay Cedex (France)
- Institut de Physique Nucleaire d'Orsay (IPNO), IN2P3- CNRS, Universite Paris Sud 11, F-91406 Orsay Cedex (France)
- Institut de Recherche en Astrophysique et Planetologie (IRAP), UMR CNRS 5187, Universite de Toulouse, 9 avenue du Colonel Roche, F-31028 Toulouse Cedex 9 (France)
- Laboratoire de Physique Nucleaire et de Hautes Energies (LPNHE) UPMC, UPD, CNRS-IN2P3, 4 Place Jussieu, F-75005 Paris (France)
Fragmentation branching ratios for channels involving H{sup +} emission and associated kinetic energy release of the H{sup +} fragment [KER(H{sup +})] have been measured for multicharged C{sub n}H{sup q+} molecules produced in high velocity (3.6 a.u.) collisions between C{sub n}H{sup +} projectiles and helium atoms. For CH{sup q+} (q{<=} 4) molecules, measured KER(H{sup +}) were found well below predictions of the simple point charge Coulomb model (PCCM) for all q values. Multireference configuration interaction (MRCI) calculations for ground as well as electronic excited states were performed which allowed a perfect interpretation of the CH{sup q+} experimental results for low charges (q = 2-3) as well as for the highest charge (q = 4). In this last case we could show, on the basis of ionization cross sections calculations and experimental measurements performed on the same systems at slightly higher velocity (4.5 a.u.), the prominent role played by inner-shell ionization followed by Auger relaxation and could extract the lifetime of this Auger relaxation giving rise to the best agreement between the experiment and the calculations. For dissociation of C{sub 2}H{sup q+} and C{sub 3}H{sup q+} with the highest charges (q{>=} 5), inner-shell ionization contributed in a prominent way to the ion production. In these two cases it was shown that measured KER(H{sup +}) were in good agreement with PCCM predictions when those were corrected for Auger relaxation with the same Auger lifetime value as in CH{sup 3+}.
- OSTI ID:
- 22068707
- Journal Information:
- Physical Review. A, Vol. 84, Issue 3; Other Information: (c) 2011 American Institute of Physics; Country of input: Syrian Arab Republic; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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