Multi-ionization of helium and lithium using the independent electron and independent event models with intrinsic CDW

Abstract

Cross sections for the multi-ionization of He and Li are presented for impact energies in the range of 50 to 1000 keV/amu. These are calculated using the eikonal initial state approximation to represent the input and exit channels of the active electrons. The ionization process is simulated in a variety of ways, most notably an attempt to account for the effects of electron correlation via the inclusion of a continuum density of states (CDS) term. Inadequacies, of the CDW formulation at small impact parameters, and of the models themselves, are discussed and conclusions are drawn on what repercussions this has for the cross sections calculated.

Classical treatment of ion-H2O collisions with a three-center model potential

“…In this respect, we have found, taking experimental data on H + + H 2 O collisions as references, that both single-and double-electron processes are better described by our implementation of the IEVM (see, however, [36,43]). The probabilities for transfer ionization (TI), double ionization (DI), and double capture (DC) are obtained following arguments similar to those leading to (8):…”

“…[33] and used in several works (e.g., [34][35][36]) for ion collisions with He. Following the interpretation of Janev et al [34], the IEVM assumes that the many-electron removal takes place sequentially.…”

“…In this respect, it is noteworthy that relevant anisotropy effects have been detected in calculations of both H + -and e-H 2 O collisions (see, e.g., [26,32]). The evaluation of inelastic probabilities for the physical many-electron system, in terms of the monoelectronic ones resulting from the model potential calculations, is performed by means of the independent-event model (IEVM) [33][34][35][36], which has been found [31,37] to be more adequate than the usual IPM for multielectronic targets.…”

Study of Inelastic Processes in Ion-H2O Collisions Using Classical Trajectory Monte Carlo and Semiclassical Methods

“…The evaluation of inelastic probabilities for the physical many-electron system, in terms of the monoelectronic ones resulting from the model potential calculations, is usually carried out by means of the IPM. In our work we have also considered the application of the so-called independent event (IEV) model, [65][66][67][68] which has been found 69,70 to be more adequate than the usual IPM for multielectronic targets.…”

Double ionization of helium by bare ions: Theoretical study of the fully differential cross sections

“…Most of the quantum mechanical calculations of σ 2+ for light targets such as He and Li were performed within the independent electron (IEL) model [8,9] or the independent event (IEV) model [9,10]. None of these models provided an ultimate description of σ 2+ at the whole range of collision energies experimentally explored [10][11][12][13][14].…”