HCI-induced molecule fragmentation: non-Coulombic explosion and three-body effects

Abstract

The study of Highly Charged Ion-induced diatomic (CO) and triatomic (CO₂) molecules fragmentation by the coincident measurement of the fragment momenta is presented. It is shown that the experimental results together with ab initio calculations including a large number of potential energy curves evidence the limitation of the Coulomb Explosion model to reproduce the dynamics of the fragmentation. The geometry modification of the CO₂ molecule during the breakup is explored and the concerted or sequential nature of the dissociation is discussed for two fragmentation channels. Finally, the fragmentation of the H₂ molecules following collisions with slow multicharged ions is analysed for various projectiles and energies. From the energy spectra, the effect of the projectile on the H⁺ fragments is evidenced. This three-body effect is discussed in connection with the results of two model calculations including or not the role of the projectile.