Photodetachment ofHe− 1s2s2p4P

Abstract

The photodetachment cross section of the 1s2s2p 4 P o metastable state of He Ϫ in the region of the 1s threshold has been calculated using our enhanced R-matrix code with the asymptotic part upgraded to handle a negative-ion system. The results show a 1s photodetachment cross section with numerous structures, completely different from similar situations in atoms or positive ions. This is found to be due to the dominance of correlation of both initial and final states of the negative ion. Specifically, interchannel coupling and a newly identified multiconfiguration overlap effect are primarily responsible for the dramatic 1s photodetachment cross-section phenomenology. Comparison with a previous calculation has been made and, while there are some areas of excellent agreement, overall there are very serious discrepancies, as much as an order of magnitude.

Inner-shell photodetachment from a Si−negative ion: strong effect of many-electron correlations

“…One can expect that the possibility of a photoexcitation to the ion state Si -* (1s 2 2s2p 6 3s 2 3p 4 4 P) reveals itself as a resonance structure in photodetachment cross sections in the energy range of the 2s and 2p inner shells thresholds similar to that in the 1s inner-shell photodetachment from C -. For the carbon ion, the strong near-threshold resonance has been predicted within the approach referred to as RPAE&DEM (Kashenock and Ivanov 2006) in a good agreement with the experiment (Walter et al 2006) and other theoretical results (Gibson et al 2003, Corgyca 2004, Zhou et al 2003. The theoretical analysis reveals the complex, mixed ("shape-Feschbach" hybrid) nature of the resonance.…”

Inner-shell resonant photodetachment of C−: the dramatic role of dynamical relaxation in collective response

“…A similar but less pronounced situation takes place (Sanz-Vicario et al 2002) regarding theoretical overestimation (Xi and Fisher 1999, Zhou et al 2001b, Zatsarinny et al 2002 of the He − cross sections just above the first K-shell threshold behind the experimental evidence (Berrah et al 2002). For the aforementioned ions the resonance structures arising from photodetachment with excitations (channels which open up due to strong correlation effects) are also observed, and the theoretical calculations using the R-matrix method and the configuration interaction (CI) approach generally have good agreement with the experimental data (Sanz-Vicario and , Bilodeau et al 2004, Lindroth and Sanz-Vicario 2004, Berrah et al 2005.…”

Inner-shell photodetachment from Ni− : A giant Feshbach resonance

“…Since they are often located very close to a threshold, the corresponding Wigner threshold behavior is severely altered by their presence as pointed out by Peterson et al [11,12]. Such shape resonances have been reported in other inner-shell photodetachment studies such as in Li ¯ [13,14,15,16], B¯ [17,18,19], C¯ [20,21,22], Fe¯ [23] and Ru¯ [24]. Both types of resonances were observed in the Pt¯ ion [25].…”