Correlated processes in inner-shell photodetachment of the Na^-ion

Abstract

We have measured the total cross section for photodetachment of the Na- ion over the photon energy range 30-51 eV. Electron detachment leads predominantly to the production of Na+ ions in this energy range. The structures in the measured cross section are associated with correlated processes involving the detachment or excitation of a 2p core electron, processes which are often accompanied by the excitation of one or more valence electrons. The most prominent feature in the cross section is a strong resonance associated with the excitation of a 2p electron from the core and a 3s valence electron. As in previous experiments on double excitation of valence electrons, electron correlation is seen to play an important role in the dynamics of negative ions.

Single and double electron photodetachment from the oxygen anion at 41.7 nm

“…Within the last decade more universal experimental setups [11,12] for detachment and ionization experiments of ionic targets in the xuv range have been realized, where intense synchrotron radiation is merged co-linearly with fast moving ion beams. With these experimental systems, benchmarking results of wavelength resolved absolute cross sections for double electron photodetachment have been obtained both for cases of inner-shell and valence-shell electron detachment [11][12][13][14][15][16][17][18][19]. Several cases of multiple electron photodetachment (n 3) have also been investigated [20][21][22][23].…”

“…For photon energy regimes where inner-shell detachments is possible, e.g., studies of He − [14], Li − [12,13], C − [15], and S − [22], the double detachment reaction mostly seems to proceed as a sequential process of inner-shell electron detachment followed by Auger decay showing, however, also delicate processes near thresholds such as the postcollisional re-capture [19,24] and the double Auger decay from a hollow resonance [18]. In contrast, for photon energy regions where valence electrons are accessed, e.g., experiments on Na − [11], F − [16], and Cl − [17], double detachment mechanisms both of indirect (sequential) nature, involving detachment into excited neutrals states followed by autoionization, and of direct nature with simultaneous emission of two electrons have been discussed. In particular, for the halogen anions F − [16] and Cl − [17] simultaneous processes are believed to dominate over sequential processes.…”

Tunneling measurements of the Coulomb pseudogap in a two-dimensional electron system in a quantizing magnetic field

“…Experimentally, inner-shell studies have been limited to the negative ions of Li − (Kjeldsen et al 2001, Berrah et al 2001, He − (Berrah et al 2002), Na − (Covington et al 2001) and C − (Gibson et al 2003). Theoretical studies have concentrated on the ions of He − (Kim et al 1997, Xi andFroese Fischer 1999) and Li − (Zhou et al 2001).…”

Single-Photon Multiple Detachment in Fullerene Negative Ions: Absolute Ionization Cross Sections and the Role of the Extra Electron

“…This sometimes dramatic difference in behavior arises from the different binding potential in negative ions. In contrast to the Coulomb potential (proportional to r À1 , with r being the distance from the nucleus) that binds the electrons in neutral and positive atoms, atomic negative ions are bound in an induced-dipole potential (proportional to r À4 ) which results in dramatic differences in the electronic structure and photodetachment dynamics [7][8][9][10][11][12][13][14][15]. On the other hand, in systems where the charge is distributed within a large, extended volume, the addition of a single electron cannot be expected to affect the spectrum significantly.…”

“…Absolute double-and triple-detachment cross sections for C 60 À ions leading to C 60 þ and C 60 2þ were measured in the photon energy range h ¼ 17-90 eV using the ionphoton-beam end station on undulator beam line 10.0.1 at the Advanced Light Source [9]. A 6 keV C 60 À ion beam was produced by evaporating 99.5% pure C 60 powder into a 10-GHz electron cyclotron resonance ion source [18], mass selected (1% resolution), and merged with a counterpropagating synchrotron radiation beam (25-90 meV bandwidth).…”