XUV photoabsorption of laser-generated W and Pt vapours

Abstract

The absorption spectra of atomic W and Pt have been recorded by the dual laser plasma technique in the range of the 4f and Sp excitations. Broad, strong and asymmetric Sp+ 5d resonances dominate the spectra. The h 4f+Sd transitions give rise to prominent maxima superimposed on the high energy slope ofthe 5p-5d resonances. Strong coupling to the Sd+ sf continuum manifests itself in the asymmetric profiles of the resonances and the extremely low cross section below the 5p onset for atomic W. The experimental results are compared to spectra calculated within the many-body perturbation theory and the relativistic random-phase approximation.

Fusion-Related Ionization and Recombination Data for Tungsten Ions in Low to Moderately High Charge States

“…Very recently, Ballance and McLaughlin have carried out large-scale R-matrix calculations for several levels of the neutral tungsten atom [65]. Their statistically weighted sum of cross-section contributions arising from different initial levels of primary tungsten atoms is in moderate agreement with the experimental results used for the comparisons (e.g., the data obtained by Costello et al [50]). Within the tungsten collisions project mentioned above, measurements on photoionization of W q+ ions in charge states q =1,2,3,4 and 5 are carried out at the photon-ion merged-beam facility of the Advanced Light Source in Berkeley.…”

“…For a demonstration of the possible modeling of the experimental results by the available theoretical approaches, Figure 10 shows the experimental result of Costello et al [50] together with the cross section for photoionization of the W(5d 4 6s 2 5 D 3 ) level calculated by Sladeczek et al [48]. The DLP measurements were not absolute.…”

“…Photoionization of neutral tungsten atoms was previously studied in the energy range from about 27 to 60 eV by Sladeczek et al [48]. Before this measurement, photoabsorption experiments with neutral tungsten in solid and vaporized forms had been performed by Haensel et al [49] and by Costello et al [50], respectively. No experimental data were available in the literature for tungsten ions prior to the present work.…”

“…Photoabsorption by tungsten atoms in the gas phase has been studied experimentally by Costello et al in the energy range from about 31 to 55 eV employing the dual-laser-plasma technique [50]. A few years after that pioneering experiment the production of W + and W 2+ photo-ions from tungsten vapor was observed by Sladeczek et al [48].…”

Photoionization of the valence shells of the neutral tungsten atom

“…However, for the single photoionization of neutral tungsten, only early experiments from the mid 1990s (which are not absolute) are available for comparison purposes. These early experiments employed a time-resolved dual-laser plasma technique to measure the photo-absorption of tungsten metal vapours [3]. These vapours were created by the ablation of a spectroscopically pure tungsten solid, subject to a flashlamp pumped dye laser.…”