1S sigma Molecular Orbital Ionisation in Asymmetric Ion-Atom Collisions by Direct Coulomb Interaction

摘要

The adiabatic perturbation theory is applied to the ionisation of the 1s sigma molecular orbital (MO) and extended to less adiabatic collisions by imposing an asymptotic matching with the semi-classical approximation. The transient molecular state wavefunction is modelled using the concept of an 'effective' charge for the colliding system. Through this procedure, the transition amplitudes are evaluated simulating both the relaxation of the passive electrons and the modification of the active electron wave-function, as well as their connection with the motion of the centre of charge during the collision. The direct Coulomb ionisation of the 1s sigma MO is calculated for projectiles following hyperbolic paths, in terms of this 'effective' charge, using the current-vector formalism. Comparison is made with a large amount of experimental data showing good agreement. (Atomindex citation 17:084350)