Photoionization of tungsten ions: experiment and theory for ${{\rm{W}}}^{2+}$ and ${{\rm{W}}}^{3+}$

Abstract

Experimental and theoretical results are reported for single-photon single ionization of W 2+ and W 3+ tungsten ions. Experiments were performed at the photon-ion merged-beam setup of the Advanced Light Source in Berkeley. Absolute cross sections and detailed energy scans were measured over an energy range from about 20 eV to 90 eV at a bandwidth of 100 meV. Broad peak features with widths typically around 5 eV have been observed with almost no narrow resonances present in the investigated energy range. Theoretical results were obtained from a Dirac-Coulomb R-matrix approach. The calculations were carried out for the lowest-energy terms of the investigated tungsten ions with levels 5s 2 5p 6 5d 4 5 D J J = 0, 1, 2, 3, 4 for W 2+ and 5s 2 5p 6 5d 3 4 F J J = 3/2, 5/2, 7/2, 9/2 for W 3+ . Assuming a statistically weighted distribution of ions in the initial ground-term levels there is good agreement of theory and experiment for W 3+ ions. However, for W 2+ ions at higher energies there is a factor of approximately two difference between experimental and theoretical cross sections.

Photoionization and photofragmentation of singly charged positive and negative Sc3N@C80 endohedral fullerene ions

“…Two permanent experimental installations were used, namely, the PIPE (Photon-Ion Spectrometer at PETRA III) endstation [30,31] of beamline P04 [32] and the IPB (Ion-Photon Beamline) endstation [33] of beamline 10.0.1. at the ALS. Several of the most recent publications of the present collaboration on photoprocesses of ions studied at the endstations at the ALS [13,[34][35][36][37] and at PETRA III [38][39][40][41][42][43] illustrate the experimental capabilities and the latest developments.…”

PAMOP Project: Computations in Support of Experiments and Astrophysical Applications

“…In Fig. 5, assuming a statistically weighted distribution of ions in the initial ground-term levels, over the energy range investigated, good agreement between theory and experiment for W 3+ ions is achieved [43].…”

Photoionization of tungsten ions: experiment and theory for ${{\rm{W}}}^{4+}$

“…The spectrum features numerous significant contributions of strong narrow resonances. Thus the character of the W 5+ photoionization cross section is strikingly different from all of the results obtained along the tungsten isonuclear sequence for W q+ with q = 0, 1, 2, 3, and 4 which are all characterized by broad cross section features, showing a transition from moderately structured spectra to mostly smooth continua as the charge q decreases [7,[11][12][13]. The experimental data were measured at a constant energy resolution which was not a priori known.…”

“…The present work provides experimental and theoretical cross sections for single-photon single ionization of W 5+ ions. It completes a series of photoionization studies on tungsten atoms [7] and ions in low charge states [8][9][10][11][12][13]. It is noted that radiative properties and core-polarization effects in the W 5+ ion have been investigated by Enzonga Yoca et al [14].…”