Electron-impact Ionization Of Hydrogen Atom Research Articles

Relativistic electron-impact ionization of hydrogen atom from its metastable 2S-state in the symmetric/asymmetric coplanar geometries

In this paper, we present a detailed analytical computation of the triple differential cross sections, in the first Born approximation, for the relativistic electron-impact ionization of hydrogen atom in the metastable 2S-state in the symmetric and asymmetric coplanar geometries. The process is investigated by using the relativistic Dirac-formalism where the effects of spin and relativity are taken into account. It is shown that the nonrelativistic limit is accurately reproduced when applying low incident kinetic energies. At high energies, relativistic and spin effects are found to significantly affect the triple differential cross sections. The numerical results obtained for the triple differential cross section are compared with some other theoretical results in the nonrelativistic regime for asymmetric coplanar geometry. For this particular process and in the absence of any experimental data and theoretical models at high energies for the triple differential cross sections, the results of our calculated relativistic total cross section are compared with available theoretical and experimental results. We hope that the present study will provide significant contribution to future experiments.

Low energy electron-impact ionization of hydrogen atom for coplanar equal-energy-sharing kinematics in Debye plasmas

Low energy electron-impact ionization of hydrogen atom in Debye plasmas has been investigated by employing the exterior complex scaling method. The interactions between the charged particles in the plasma have been represented by Debye-Huckel potentials. Triple differential cross sections (TDCS) in the coplanar equal-energy-sharing geometry at an incident energy of 15.6 eV for different screening lengths are reported. As the screening strength increases, TDCS change significantly. The evolutions of dominant typical peak structures of the TDCS are studied in detail for different screening lengths and for different coplanar equal-energy-sharing geometries.

Influence of renormalization shielding on the electron-impact ionization process in dense partially ionized plasmas

The renormalization shielding effects on the electron-impact ionization of hydrogen atom are investigated in dense partially ionized plasmas. The effective projectile-target interaction Hamiltonian and the semiclassical trajectory method are employed to obtain the transition amplitude as well as the ionization probability as functions of the impact parameter, the collision energy, and the renormalization parameter. It is found that the renormalization shielding effect suppresses the transition amplitude for the electron-impact ionization process in dense partially ionized plasmas. It is also found that the renormalization effect suppresses the differential ionization cross section in the peak impact parameter region. In addition, it is found that the influence of renormalization shielding on the ionization cross section decreases with an increase of the relative collision energy. The variations of the renormalization shielding effects on the electron-impact ionization cross section are also discussed.

Exchange effects in electron-impact ionization of atomic hydrogen.

A method for obtaining the exchange scattering amplitude for electron-impact ionization of atomic hydrogen in the eikonal approximation is developed. The expression for the eikonal amplitude in the present case turns out to be a two-dimensional integral which can be evaluated numerically with convenience. This exchange amplitude can be combined with the corresponding direct amplitude to calculate both differential and total cross sections for electron-impact ionization of hydrogen atoms. We present numerical results for triply differential cross sections (TDCS) for the H(e,2e)${\mathrm{H}}^{+}$ process for incident energies of 150 and 250 eV. A comparison is made of the present TDCS with the corresponding results of other calculations and experiment.

Spin asymmetry in electron-impact ionization of hydrogen atoms close to threshold.

I report the results of a calculation of the spin asymmetry in the electron-impact ionization of hydrogen atoms for incident energies between 14 and 20 eV. The work involves a variational close-coupling calculation with a pseudostate basis, supplemented by an optical potential procedure for higher partial waves.

Triply-differential cross sections for electron-impact ionization of atomic hydrogen

A method for obtaining triply-differential cross sections (TDCS) for electron-impact ionization of atomic hydrogen in the Glauber approximation is developed. The expression for the Glauber amplitude in the present case turns out to be a simple two-dimensional integral which can be accurately evaluated. The present procedure has an advantage over the conventional partial-wave technique in calculating TDCS in that the latter requires substantial computer time where many partial waves are involved. We present numerical results for electron-impact ionization of hydrogen atoms at incident energies of 100, 113.6, and 250 eV. A comparison is made of the present TDCS with the corresponding results of the first Born approximation and experiment.