C. R. Mandal

Inelastic processes in the interactions of partially stripped ions of carbon, nitrogen and oxygen with atomic hydrogen at intermediate and high energies

The classical trajectory Monte Carlo (CTMC) simulation method has been employed to study the sub-shell distributions of total charge transfer cross sections and total ionization cross sections in collisions of partially stripped ions of carbon, nitrogen and oxygen in different charge states (q ≤ 5) with ground state atomic hydrogen in the energy range 10-200 keV amu-1. The total cross section for charge transfer and ionization has been found to be in good agreement with the experimental observations as well as with other theoretical findings. Due to the non-availability of any other experimental results for sub-shell distributions of charge transfer cross sections, comparisons have been made with other existing theoretical results. The observations have been found to be satisfactory. However, an oscillatory structure of the charge-state dependence of the total cross sections has not been found in our calculation.

Four-body charge transfer processes in collisions of bare projectile ions with helium atoms

Single-electron capture by a bare ion from a helium atom at intermediate and high energies in the framework of four-body distorted wave (DW-4B) approximation in both prior and post form has been considered. In the entrance channel, the initial bound state wave function is distorted by the incoming projectile ion, and the corresponding distortion is related to the Coulomb continuum states of the active electron and the residual target ion in the field of the projectile ion respectively. Continuum states of the active electron and the projectile ion in the field of the residual target ion are also included in the exit channel. It may be mentioned that the effect of dynamic electron correlation is explicitly taken into account through the complete perturbation potential. The total single-electron capture cross sections are obtained by summing over all contributions up to n = 3 shells and sub-shells respectively. In addition, the differential cross sections for alpha particle?helium collision are calculated at impact energies of 60, 150, 300, 450, and 630 keV amu?1, respectively. The cross sections exhibit a monotonically decreasing angular dependence, with clear peak structures around 0.1 to 0.2 mrad being found at low impact energies. The current theoretical results, both in prior and post forms of the transition amplitude for symmetric and asymmetric collision, are compared with the available theoretical and experimental results. Current computed results have been found to be satisfactory in comparison with other theoretical and experimental findings.

State-selective electron capture in the interactions of partially stripped ions of beryllium and boron with atomic hydrogen in the ground state

The Coulomb-Born approximation has been employed to study charge transfer cross sections in the case of collisions of (q = 1-3) and (q = 1-4) with atomic hydrogen in its ground state, respectively, within the energy range of . The interaction of the active electron with the incoming projectile ion has been approximated by a model potential. Cross sections for capture into different sub-shells have been given in tabular form. Computed total capture cross sections compare favourably with existing available results.

Single ionization of helium by positron and electron impact

Four-body formalism of Boundary Corrected Continuum Intermediate State (BCCIS-4B) approximation is introduced to study the (e, 2e) reaction for Helium targets. The influence of the description of the ejected electron on triple differential cross sections is analyzed.

Single-electron-capture processes in collisions of He{sup 2+}, Li{sup q+} (q=1,2,3), C{sup 6+}, and O{sup 8+} ions with helium

Cross sections for single-electron capture in collisions of He{sup 2+}, Li{sup q+} (q = 1,2,3), C{sup 6+}, and O{sup 8+} ions with helium atoms at incident energy ranging from 50 to 5000 keV/amu have been calculated in the framework of four-body boundary-corrected continuum intermediate state (BCCIS-4B) approximation in both prior and post forms. In this formalism, distortion in the final channel related to the Coulomb continuum states of the projectile ion and the active electron in the field of residual target ion are included. In all cases, total single-electron-capture cross sections have been calculated by summing over all contributions up to n = 3 shells and subshells, respectively. It has been observed that the contribution of the capture cross section into the excited states is significant for asymmetric collision (Z{sub P}>Z{sub T}) and is insignificant for symmetric collision. Numerical results for the total cross sections show good agreement with the available experimental findings, particularly in the post form. Post-prior discrepancy has been found to be within 30% except for Li{sup +} + He interactions below 150 keV/amu.