S Legendre et al 2005 J. Phys. B: At. Mol. Opt. Phys. 38 L233 doi:10.1088/0953-4075/38/14/L01
S Legendre, E Giglio, M Tarisien1, A Cassimi, B Gervais and L Adoui
Show affiliationsWe investigate fast, highly charged ion-induced HOD molecule fragmentation dynamics. Focusing on double ionization of the molecule, we evidence a strong preferential cleavage of the O–H bond rather than the O–D bond. We find an isotopic branching ratio defined as the number of H+ + OD+ over D+ + OH+ dissociations of 6.5 ± 0.5. Moreover, the coincident measurement, by imaging techniques, of high-resolution kinetic energy release (KER) distributions for different fragmentation channels shows, for the first time, a clear difference of approximately 1 eV between the mean KER value of the two-body dication fragmentation channels H+ + OD+ and D+ + OH+. We analyse the two aspects of this isotopic effect by means of a semi-classical calculation simulating the dissociation dynamics via the dication electronic ground state. The final pathway is found to be strongly correlated to the initial position and momentum distributions. Those correlations explain both the observed O–H bond preferential cleavage and, for a large part, the different mean KER values. The other part of the 1 eV kinetic energy difference results from different vibrational energies of the residual molecular fragment that have also been estimated.
31.30.Gs Hyperfine interactions and isotope effects
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
34.50.Gb Electronic excitation and ionization of molecules
33.15.Fm Bond strengths, dissociation energies
31.50.Bc Potential energy surfaces for ground electronic states
Issue 14 (28 July 2005)
Received 26 April 2005, in final form 7 June 2005
Published 27 June 2005
S Legendre et al 2005 J. Phys. B: At. Mol. Opt. Phys. 38 L233
Claus Kiefer 2004 Class. Quantum Grav. 21 L123
V.A. Zhil'tsov et al 2000 Nucl. Fusion 40 509
G Georgiev et al 2005 J. Phys. G: Nucl. Part. Phys. 31 S1439
Qing Ren et al 2007 Phys. Med. Biol. 52 6651
J H Nixon 1991 J. Phys. A: Math. Gen. 24 2913
Luc Belloni 2002 J. Phys.: Condens. Matter 14 9323
Christian Brouder 2007 J. Phys. A: Math. Theor. 40 9455
Silvio De Siena et al 2001 J. Phys. B: At. Mol. Opt. Phys. 34
J M Christian et al 2007 J. Phys. A: Math. Theor. 40 8601