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

Abstract

Experimental and theoretical cross sections are reported for single-photon single ionization of W 5+ ions. Absolute measurements were conducted employing the photon-ion merged-beams technique. Detailed photon-energy scans were performed at (67±10) meV resolution in the 20 -160 eV range. In contrast to photoionization of tungsten ions in lower charge states, the cross section is dominated by narrow, denselyspaced resonances. Theoretical results were obtained from a Dirac-Coulomb R-matrix approach employing a basis set of 457 levels providing cross sections for photoionization of W 5+ ions in the 4f 14 5s 2 5p 6 5d 2 D 3/2 ground level as well as the 4f 14 5s 2 5p 6 5d 2 D 5/2 and 4f 14 5s 2 5p 6 6s 2 S 1/2 metastable excited levels. Considering the complexity of the electronic structure of tungsten ions in low charge states, the agreement between theory and experiment is satisfactory.

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.…”

Electron-impact single ionisation of W q+ions: experiment and theory for 11 ≤ q ≤ 18

“…Motivated by the importance of tungsten in modern fusion research, a comprehensive experimental programme on studying electron-ion recombination [24][25][26], electron-impact ionisation [27,28] and photoionisation [29][30][31][32] of tungsten ions has been launched [1]. As a part of this campaign, the present study addresses electron-impact single ionisation (EISI) of W q+ ions with charge states   q 11 18, thus, extending previous experimental work on EISI of tungsten ions with charge states in the range 1-10 [33].…”

Photoionisation of Ca+ions in the valence-energy region 20–56 eV: experiment and theory

“…Experimental methods for studying photoabsorption by ions and typical results of such experiments have been reviewed by Müller et al [46,47]. The most recent publication of experimental results from the IPB addressed PI of W 4+ ions [48]. The general layout of the IPB setup and the associated experimental procedures were described in detail by Covington et al [49].…”

“…The DARC suite of codes allows high-quality PI cross section calculations to be performed on heavy complex systems. PI cross-section calculations of Se 71], and Co + [72], valence-shell studies on neutral sulfur [73], sulfur-like chlorine, Cl + [74], copper-like zinc, Zn + [75], tungsten and its ions, W [76] [48] and W 63+ [78] have been made using these DARC codes. Suitable agreement of the DARC PI cross-sections with high resolution measurements performed at leading synchrotron light sources was obtained.…”