On the application of relaxed-orbital and sudden perturbation approximations for the photoionization of atoms

Abstract

The outermost closed subshell photoionization cross sections from He, Li, Na and K atoms and asymmetry parameters β of the 2p photoionization from Na atoms are calculated applying both relaxed-orbital Hartree-Fock (ROHF) and sudden perturbation (SP) approximations. The suitability of both methods for the calculation of a single photoionization and shake-up cross sections is considered, and differences between these and frozen orbital approximations are discussed. The higher accuracy of the ROHF approximation with respect to that of SP is found near the threshold of ionization. The SP approximation can be used only for high photon energies. The weak dependence of the parameter β on the applied method (ROHF or SP) is noticed.

Investigation of fluorescence radiation following radiative recombination of ions and electrons

“…The reduced matrix elements in B ph (2, 0, 0, 2, 0, 2, 2, 1, 1) (7) were calculated by using a computer program for the photoionization of atoms [9]. For the calculation of (13) - (15), a computer program was created in the present work.…”

“…The asymmetry parameters β 2 (13) of the angular distribution for PRF in the case of PR of bare nuclei and nonpolarized Ne-like ions Na + , Mg 2+ , Al 3+ , Ar 8+ , Fe 16+ , and Zn 20+ with nonpolarized electrons were calculated. The reduced matrix elements in B ph (2, 0, 0, 2, 0, 2, 2, 1, 1) (7) were calculated by using a computer program for the photoionization of atoms [9]. For the calculation of ( 13) -( 15), a computer program was created in the present work.…”

Atomic theory methods for the polarization in photon and electron interactions with atoms

“…The expressions for β (53) and σ (54) differ from those obtained in [26] and used in the calculations of the angular distribution of 2p photoelectrons from Na atoms in the ground [80] and excited states [80][81][82]. The spin polarization parameters γ, δ, and ξ were also calculated for the 2p photoionization of Na in the ground and first excited states [83].…”

Theoretical study of 4p5nln'l'LSJstates of Sr ion excited by electron impact on Sr atom

“…A simultaneous ionization and excitation (SIE) process very effective in light alkali atoms [18] can also populate the states of Sr ion: Sr(4p 6 5s 2 1 S 0 ) + e → → Sr + (4p 5 5snlLS(J = 1/2, 3/2)) + e' + e''.…”