Differential cross sections for single ionization of Li in collisions with fast protons andO8+ions

Abstract

We study the process of single ionization of Li in collisions with H + and O 8+ projectile ions at 6MeV and 1.5-MeV/amu impact energies, respectively. Using the frameworks of the independentelectron model and the impact parameter picture, fully (FDCS) and doubly (DDCS) differential cross sections are evaluated in the continuum distorted-wave with eikonal initial-state approxima- respectively. For O 8+ impact inclusion of the heavy particle (NN) interaction in the calculations is crucial and effects of polarization due to the presence of the projectile ion have also to be taken into account for getting very good agreement with the measured data. Our calculation reproduces the satellite peak structure seen in the FDCS for the Li(2s) measurement, which we explain as being formed by a combination of the binary and NN interactions.

Theoretical investigation of the fully differential cross sections for single ionization of He in collisions with 75-keV protons

“…In the present work, in addition to the Coulomb field, a short-range potential is also introduced for a more realistic account of the core electron. Moreover, the polarization of the target core ion by the incident projectile ion is taken into account by a polarization potential [27][28][29]. The indication of single-center interference and the characteristic role of target core polarization are observed at small and large momentum transfer values.…”

Doubly differential cross sections for ionization of lithium atom by protons and O8+ ions

“…Different types of the semiempirical NN potentials were examined in Ref. [9]. It was found that at small momentum transfers, the DDCS is sensitive solely to the asymptotic form of the NN potential at large internuclear distances.…”

Doubly-differential-cross-section calculations forK-shell-vacancy production in lithium by fastO8+-ion impact

“…1(c)-3(c) of Ref. [12] for the valence-shell ionization DDCSs] by combining the outer-shell ionization amplitude with amplitudes for inner-shell excitations and elastic scattering. While all the processes from (i) to (iv) play an important role in increasing the overall DDCS to match the experimental values at low η, it is the EI2 process that is responsible for the broadening of the DDCS such that it agrees well with the experiment at E e = 2 eV (Fig.…”

“…With this new approach the first kinematically complete experiment for single ionization of lithium was achieved and experiments were performed for the H + -Li collision system at 6 MeV/amu [6], the O 8+ -Li collision system at 1.5 MeV/amu [6,7], and the Li 2+ -Li collision system at 2.29 MeV/amu [8]. This triggered theoretical efforts for the interpretation of the experimental data [8][9][10][11][12].…”

“…At the level of the singly differential cross section (SDCS) outershell ionization has proven to be nearly a single-electron process with a marginal influence of the K-shell electrons [11]. Yet, doubly differential cross sections (DD-CSs) for outer-shell ionization show that the inner-shell electrons do play a role in the process, e.g., via core polarization by the projectile [12]. In K-shell vacancy production, on the other hand, the effects of the presence * macieks@yorku.ca † tomk@yorku.ca of all electrons are important already at the level of the SDCS [11].…”