Single and double ionization inC6++Hecollisions

Abstract

Single-and double-ionization processes in C 6+ collisions with the He atom at an incident energy of 100 MeV/amu are studied by direct solution of the time-dependent Schrödinger equation. A time-dependent close-coupling method based on an expansion of a one-electron three-dimensional wave function in the field of He + is used to calculate single-ionization cross sections. A time-dependent close-coupling method based on an expansion of a two-electron six-dimensional wave function in the field of He 2+ is used to calculate single-and double-ionization cross sections. Electron energy and angle differential cross sections for single ionization are presented for various projectile impact parameters. For relatively large impact parameters, the differential cross sections are in qualitative agreement with ion-atom experiments. Electron energy and angle differential cross sections for double ionization are also presented for a relatively large projectile impact parameter.

Fully differential cross sections for the single ionization of He by C6 +ions

“…Also, using the full target charge (i.e. Z eff = 2.0) in equation (12) gives similar results to calculations presented in figure 3.…”

“…This is not surprising, as by 30 au, the single-ionization probability has dropped significantly, as shown in figure 5, and is almost two orders of magnitude lower than at the peak of the probability distribution, which occurs near b = 1.0 au. Furthermore, very large impact parameters correspond to very small momentum transfers [12], so we do not expect large impact parameters to contribute to the FDCS at the current momentum transfer value of 0.75 au.…”

“…In equation 8, δ l is a distorted-wave phase which is due to the V l (r) potential. Our approach up to now is identical to our previous work [12], in which differential cross sections were presented for single ionization of helium at specific impact parameters. If we now wish to obtain cross sections differential with respect to the momentum transfer (η) of the projectile, we must perform a Fourier transform of the function in equations (8) and (9) [13].…”

Fully differential cross section for O8+-impact ionization of Li

“…On one hand, the TDCC method based on an expansion of a one-electron threedimensional wave function was used in single ionization processes in single electron systems, namely H [2] and H + 2 [3], and in the single active electron approximation in He [2], Li [2] and H 2 [4]. On the other hand, the TDCC method based on an expansion of a two-electron sixdimensional wave function was applied to single and double ionization ionization processes in He [2,[5][6][7][8][9] and H 2 [3,4,10]. The TDCC method based on an expansion of a two-electron six-dimensional wave function scheme represents a challenge from a computational viewpoint and massive parallel computers are employed to obtain the theoretical quantities needed to compare with the experimental measurements.…”

Differential cross sections for single ionization of H2by 75-keV proton impact

“…Theoretically many different approaches have been used to calculate TDCS for ionimpact ionization of atoms such as the First born approximation-Hartree Fock (FBA-HF) [7], the continuum distorted wave (CDW) [20], the continuum distorted wave-Eikonal initial state (CDW-EIS) [2,11], the three coulomb wave Hartree Fock (3C-HF) [7], the 3DW-EIS (3-body distorted wave-Eikonal initial state) [1,8], and a non-perturbative TDCC (time dependent close coupling) approach [21].The FBA is only valid at sufficiently large projectile energies for higherorder contributions to be small. The CDW-EIS/3DW-EIS approach accounts for higher order effects in both the initial and final states, but it is effectively a 2-state approximation neglecting couplings to excited states other than the continuum states of interest.…”