Orientation Effects in Multiple Ionization of Molecules by Fast Ions

Abstract

The multiple ionization and dissociation of N 2 molecules by fast He 1 ions was studied by the coincident measurement of correlated fragment-ion momenta using a position-and time-sensitive multiparticle detector. The dependence of the cross section on the alignment of the molecular axis with respect to the beam axis was determined. The results show that for higher degrees of ionization the cross section has a pronounced minimum for molecules oriented perpendicular to the beam. The quantitative interpretation of the observed results is based on an extended version of the statistical energy deposition model. [S0031-9007(97)03955-0]

Setup for measuring angular anisotropies in slow ion-molecule collisions

“…Several aspects of ion-impact molecular dissociation have been addressed using these powerful instruments, such as limitations of the Coulomb explosion model to reproduce molecular fragmentation dynamics [4], orientation effects in multiple ionization of molecules by fast ions [5] and studies on intra-molecular bond rearrangements in ion-molecule collisions [6].…”

Orientation and impact-parameter dependence of dissociative ionization of H2by slow ion impact

“…Thus the measured break-up pattern yields the complete information on the orientation of the molecular system with respect to the ion beam axis. A first quantitative measurement of vector correlation following ion-induced molecule fragmentation has been reported in pioneering experiments by Werner et al [27].…”

Multiple Ionisation and Fragmentation of Molecules

“…The alignment dependence for N 2+ -N 3+ shows a pronounced minimum at the perpendicular orientation. The origin of this strong orientation effect is due to the anisotropy of the electron density distribution (Wohrer and Watson 1993;Werner et al . 1997a) and the related anisotropy of the energy deposition along a trajectory.…”