On the application of relaxed-orbital Hartree-Fock approximation for the ionization cross sections of atoms

The quantal theory of the continuous photo-electric absorption of radiation is briefly summarized, pàrticular attention being given to the alternative formulae available and to the accuracy to be expected in practical calculations. Detailed calculations are described for the photo-ionization cross-section of neon, a system for which it is understood that experimental data should be available in the near future. The calculation is made using Hartree-Fock wave functions and the two formulae of the dipole length and the dipole velocity. The corresponding cross-sections are found to be 5.8 and 4.4 x 10- 18 cm 2 . at the spectral head and to rise slowly with increasing frequency until a broad maximum is reached for an energy of the ejected electron of about 11 eV. A comparison is made with previous calculations on the elements from boron to neon ; the general trend of the results is discussed and improved estimates for boron and fluorine are given (10 x 10 -18 cm 2 . for boron and 4.3 x 10- 18 cm 2 . for fluorine at the spectral head).

Download Full-text

Electron impact total and ionization cross sections for Sr, Y, Ru, Pd, and Ag atoms

Canadian Journal of Physics ◽

10.1139/cjp-2013-0174 ◽

2013 ◽

Vol 91 (9) ◽

pp. 744-750 ◽

Cited By ~ 7

Author(s):

Dhanoj Gupta ◽

Rahla Naghma ◽

Bobby Antony

Keyword(s):

Electron Impact ◽

Cross Sections ◽

Optical Potential ◽

Atomic Orbital ◽

Atomic Charge ◽

Ionization Cross ◽

Charge Densities ◽

Hartree Fock ◽

Spherical Complex ◽

Ionization Cross Sections

Calculation of electron impact total and ionization cross sections for Sr, Y, Ru, Pd, and Ag atoms were performed using spherical complex optical potential and complex scattering potential-ionization contribution methods. The complex optical potential model is formulated from the target parameters and the atomic charge density. The spherical charge densities are in turn derived from the Roothaan–Hartree–Fock wavefunctions defining the atomic orbital of the target. In the present study cross sections are computed in the energy range from ionization threshold to 2000 eV. The results obtained are compared with other theories and measurements wherever available and were found to be quite consistent and uniform. In general, present data show an overall reasonable agreement with other results. Dependence of total cross sections on the number of target electrons and peak of ionization cross section on target parameters were also found to be consistent with previous observations.

Download Full-text

He2+ Impact Single Ionization Cross Sections of Fe Atom

Journal of Nepal Physical Society ◽

10.3126/jnphyssoc.v6i2.34868 ◽

2020 ◽

Vol 6 (2) ◽

pp. 127-133

Author(s):

S. P. Gupta ◽

K. Yadav ◽

R. Khanal ◽

L. K. Jha

Keyword(s):

Energy Range ◽

Cross Sections ◽

Impact Energy ◽

Theoretical Calculations ◽

Ionization Cross ◽

Single Ionization ◽

Hartree Fock ◽

Ionization Cross Sections ◽

Binary Encounter Approximation ◽

The Given

Binary encounter approximation has been used for theoretical calculations of alpha particle (He2+) impact single ionization cross sections of iron atom at ground state in the energy range of 35 to 360 keV/amu. The cross sections for energy transfer given by Vriens’ and quantum mechanical Hartree-Fock velocity distributions for target electron have been used in the calculation. The contributions in total single ionization cross sections from 4s and 3d subshells are observed to be higher than from 3p, and the contributions from 4s decreases with increase of impact energy whereas the contribution from 3d increases. The total single ionization cross sections decrease gradually with the increase of impact energy similar to experimental results which implies that our results are in satisfactory agreement with the experimental data in the given energy range.

Download Full-text