Potential-Barrier Effects in Photoabsorption. II. Interpretation of Photoabsorption Resonances in Lanthanide Metals at the4d-Electron Threshold

Core and shallow-cored- tof-shell excitations in rare-earth metals

“…By contrast, the higher energy spectral structure (>115 eV) is influenced by more extended final states that interact with the continuum bands, giving rise to Fano resonances and clearly leaving the ionic limit [29,[49][50][51][52].…”

Perturbation theory in a strong-interaction regime with application to 4d-subshell spectra of Ba and La

“…Finally, the decay of each of the term levels of the 4d 9 4f N + 1 configuration lying above threshold, via reaction (1.2), was treated by ordinary techniques of scattering theory (Starace 1972, Dehmer andStarace 1972). This theoretical interpretation of Dehmer et al (1971) was bolstered by the excellent agreement between the observed spectroscopic structure and the predictions of Sugar (1972) for the term energies and oscillator strengths of the intermediate configuration 4d 9 4f N + 1 . A controversy arose when the above theory was used by experimentalists to interpret their data on the 4d-subshell photoabsorption spectrum of barium (Connerade and Mansfield 1974, Ederer et al 1975, Rabe et al 1974.…”

“…The controversy relates to the theoretical interpretation by Dehmer et al (Dehmer et al 1971, Starace 1972, 1974, Sugar 1972, Dehmer and Starace 1972 of the 4d-subshell photoabsorption spectra of the rare earths (57 ≤ Z ≤ 70). In brief, Dehmer et al (1971) interpreted these experimental spectra , Haensel et al 1970, Gudat and Kunz 1972 as resulting from a simple two-step process: photoexcitation of a 4d-subshell electron into the 4f subshell, i.e.…”

“…This theory assumed the use of a single basis set of one-electron orbitals (such as that provided by an average-of-configuration Hartree-Fock calculation). The energies of the various term levels of the intermediate configuration 4d 9 4f N + 1 were obtained by diagonalizing the energy matrix within this configuration (Sugar 1972, Starace 1974. Electrostatic interactions within the intermediate configuration were found to be so strong that many of the higher-term levels were shifted above the 4d 9 4f N threshold, as defined of course in the one-electron basis.…”

The effect of viewing angle on the spectral behavior of a Gd plasma source near 6.7 nm

“…As described by Filevich et al [13], EUV emission from laser-produced plasmas creates a cold plasma on the target surface dominated by low ion stages. As the photoabsorption profile of neutral to 3 times ionized Gd consists of giant resonances in the 7−9 nm range with cross sections up to tens of Mb [14][15][16], radiation trapping by low ion stages may considerably reduce the observed intensity in this region. …”