The Kα
satellite spectra arising from the correlative multielectron processes accompanying
K-shell photoionization of Ca, Ti and V were measured using a broad range crystal
spectrometer. Multiconfiguration Dirac–Fock calculations were performed to
interpret the observed x-ray energies and the spectral line shape. The calculations
agree fairly well with the experimental results. The variation of the Kα
L1 satellite and the
Kα1,2h
hypersatellite intensities was measured as a function of
excitation energy in the range of 8–35 keV. The Kα
L1/Kα1,2 intensity
ratio for each element is already saturated in our energy range, and the asymptotic values of
1.58 ± 0.08,
1.26 ± 0.06 and
0.97 ± 0.05
% for Ca, Ti and V were determined. By combining the present results and
the previously measured values for various elements, we have found a
Z−3.5 scaling
law for the Kα
L1/Kα1,2
intensity ratio. The measured Kα1,2h/Kα1,2
intensity ratio, for each element, is found to increase smoothly from its
onset and shows a long saturation range extending up to at least 25
keV above the threshold for Ti. The evolution of the Kα1,2h/Kα1,2
intensity ratio is compared with the analytic Thomas model and with the
theoretical calculation based on the screened hydrogenic model.
Using a photon-ion merged-beam technique, we measured the relative yield spectra of Xe 2+ and Xe 3+ ions created by photoionization of Xe + ions as a function of the photon energy in the 4d ionization region. The Xe 3+ ion production, i.e. the double-electron ionization process is found to be dominant throughout the energy range investigated. A broad structure of 4d excitation ionization around 100 eV photon energy was observed in the Xe 3+ yield spectrum. A spectral shoulder was observed for Xe 3+ at around 85 eV, which was absent in the photoionization of neutral Xe. Some discrete lines were observed for both the Xe 2+ -and Xe 3+yield spectra below 75 eV. The experimental spectra were analysed by a multiconfiguration Dirac-Fock calculation. The largest structure at around 100 eV is attributable to 4d 10 5s 2 5p 5 → 4d 9 4f5s 2 5p 4 np (n = 6, 7) two-electron transitions. The discrete lines were found to be due to 4d → np, nf transitions. A serious 4f-orbital collapse is suspected in the 4fnp two-electron excited states, whereas the collapse is moderate in the singly excited 4f-orbitals.
Photoion spectrometry has been applied to determine the relative photoionization yields of Ba+ ions around the 4d ionization threshold. A ground state Ba+ ion beam was merged with monochromatized synchrotron radiation over a length of 15 cm. Counting the number of doubly and triply charged ions produced in the interaction region, we have obtained partial photoion yields as a function of photon energy. Prominent peaks due to resonance Auger processes have been observed below the threshold. A giant resonance structure above 4d threshold was seen only for the Ba3+ spectrum.
The photoion yields from O+ to O2+ were measured in the 1s–2p autoionizing
resonance region of the 525–540 eV photon energy range. A multiconfiguration
Dirac–Fock calculation was performed to interpret the experimental data
and the results show fairly good agreement with the experimental ones.
Photoionization of the N-like isoelectronic sequences of O+ and Ne3+ are discussed.
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