Autoionisation of N⁵⁺(3ln'l') for n'=3-10: experiment and theory

Abstract

The energy values of the autoionisation states (3h'l') of the N5+ ion are deduced from the analysis of ejected-electron spectra following the collisional electron charge transfer process between bare N7+ projectiles and various targets (He, H, and Ar). We compare these results with our ab initio theoretical calculations employing a fourteen-state pseudostate close-coupling scheme.

Calculations of doubly excited states in helium-like systems using Hylleraas functions

“…Such structures were partly due to, according to our calculations, the 3 F o (4), 1 F o (3), 1 F o (4), 1 F o (7) and 1 F o (8) states with energies of 77.10, For resonances below the N = 4 threshold, we compare our results in tables 12 and 13 with those in the literature for O 6+ and Ne 8+ , respectively. In table 12, we compare our 1,3 F o (4 5 ) states for O 6+ with those of van der Hart et al (1994). In general, the agreements are quite good, with the exception of the widths for the 1 F o (6) and 1 F o (7) states.…”

“…The resonance positions between these two calculations differ to within 0.2 eV, with the exception of the 3 F o (1) state having a difference of slightly more than 0.2 eV. Also, Oza et al (1988) did not report results for all the doubly excited n n states with n = 3, n 5. According to our calculations, the states they calculated…”

“…As for the other systems, Bachau's widths agree with our results better for high Z systems than for low Z ions. A 14-state pseudostate close-coupling calculation (Oza et al 1988) was carried out for Z = 7 for states below the N = 3 threshold of N 6+ ions. A comparison of their results for five 1 F o and three 3 F o states is given in table 10.…”

“…The energy (in eV) is measured from the N = 2 threshold of the N 6+ ion. We retain three to five significant figures in line with those given in Oza et al (1988) for comparison purposes. In general, the agreement between these two calculations is quite good.…”

Doubly-excited state resonances of the helium-like nitrogen ion N5+ near then=3 threshold of N6+

“…In their work, Tsurubuchi et al [1] have observed a peak corresponding to (3/3 l') autoionisation states of N 5 + by performing energy gain spectroscopy of the fast ion in the collisions between N 7+ and He. By collision between bare N 7 + ions and a two electron target (He and H2), Bordenave-Montesquieu et al [2][3] have observed in ejected electron spectra excited states formed by two-electron capture, which states are autoionising configurations of N s+ (nln'l') with n = 2, 3, 4 and n'> n. Others experimental investigations on the He-like nitrogen ion have also been made by Benoit-Cattin et al [4], Oza et al [5], and by MorettoCapelle et al [6].…”