Photoionization energies and oscillator strengths of helium and helium-like ions with Z=6-8

摘要

In the photoionzation process of helium and helium-like ions with Z = 6-8 (C4+, N5+, O6+), resonance energies of doubly excited autoionizing P-1.3 degrees states converging on the n = 4 and n = 5 hydrogenic thresholds are calculated by use of the diagonalization method. We evaluate also the oscillator strengths for transitions from 1s(2) (Se-1) to continuum 1s epsilon p (P-1 degrees) state. The calculations are done with the dipole length and velocity formulas using the six-parameter Hylleraas wave function For the ground state. The continuum state is represented by an antisymmetrized product of hydrogenics wavefunctions with a completely screened Coulomb functions. and the autoionizing states by wavefunctions constructed in the diagonalization approximation within the framework of the theory of configuration interaction.