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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.

The Kalpha 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 KalphaL(1) satellite and the Kalpha(1,2)(h) hypersatellite intensities was measured as a function, of excitation energy in the range of 8-35 keV. The KalphaL(1)/Kalpha(1,2) 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 KalphaL(1)/Kalpha(1,2) intensity ratio, The measured Kalpha(1,2)(h)/Kalpha(1,2) 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 Kalpha(1,2)(h)/Kalpha(1,2) intensity ratio is compared with the analytic Thomas model and with the theoretical calculation based on the screened hydrogenic model. (Less)

Multiply charged ions for some gaseous and metallic elements have been produced as the target for photoionization studies using synchrotron radiation. The target densities have been measured to be typically of the order of 106 ions/cm3. Characteristics of the beam transport system is described and the feasibility of photoionization experiments along the isonuclear and the isoelectronic sequences is also discussed.

Using an ion-photon merged-beam apparatus, photoion yield spectra of and from the 4d photoionization of were measured as a function of photon energy in the range 110-160 eV. The measured spectra look very similar to those from a neutral Eu target. Both and yield spectra, a broad `giant resonance' appears at 140 eV with some preceding small peaks at 131.5, 132.8 and 134.7 eV. The summit of the `giant resonance' in the spectrum is split into two peaks. This is not observed in neutral Eu photoionization.

Using a photon - ion merged-beam technique, we measured the relative yield spectra of and ions created by photoionization of ions as a function of the photon energy in the 4d ionization region. The 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 yield spectrum. A spectral shoulder was observed for at around 85 eV, which was absent in the photoionization of neutral Xe. Some discrete lines were observed for both the - and -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 (n=6,7) two-electron transitions. The discrete lines were found to be due to , n f transitions. A serious 4f-orbital collapse is suspected in the 4 fn p two-electron excited states, whereas the collapse is moderate in the singly excited 4f-orbitals.

Using a photon-ion merged-beam apparatus, the relative photoion-yield spectra for doubly- and triply-charged ions from Xe+, Ba+ and Eu+ ions were measured in the 4d ionization region. The giant resonance peak appears for all target ions. The peak of Xe+ is broad and that of Eu+ is relatively narrow, similar to those observed in the neutral atoms. The spectrum of Xe3+ shows some structures around 87 and 93 eV. The summit of the giant resonance peak of Eu2+ is obviously split into two. These structures observed in the Xe3+ and Eu2+ spectra are not observed in the photoion spectra of the neutral targets. Some small peaks are observed in the Xe+ spectrum between 70 and 76 eV. A multi-configuration Dirac-Fock calculation reveals that these peaks are attributed to 4d-np and 4d-nf transitions. It was also found that the broad peak centered at 100 eV corresponds to shake-up resonance (4d105s25p5→4d94f5s25p4np [n=6.7]) processes. Some prominent peaks that do not appear in the neutral Ba spectrum are observed clearly in the Ba+ one. These peaks are most probably due to the 4d-nf transition followed by Auger processes.

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.

In order to study the photoionization of multiply charged ions (MCI) by synchrotron radiation, a collinear ion-photon merging-beam (MERGING) system and an electron beam ion source (EBIS) have been developed and constructed. Their main features are described including preliminary results of test experiments.

Multiply charged ions of Xe gases were produced through inner‐shell photoionization by using synchrotron radiation, and were stored in an rf ion trap. The experimental apparatus for trapping and probing multiply charged ions is described, and results for the measurements on the mass spectra of trapped ions and lifetime of each charge state are presented.

Photoion yields from ${\mathrm{Ne}}^{+}$ to ${\mathrm{Ne}}^{2+}$ and from ${\mathrm{Ne}}^{2+}$ to ${\mathrm{Ne}}^{3+}$ were measured near the K-shell $(1s\ensuremath{-}2p)$ autoionizing resonance region in the 841--858-eV and 850--863-eV photon energy range, respectively. Measurements were performed using a photon-ion merged-beam apparatus with an electron cyclotron resonance ion source. Multiconfiguration Dirac-Fock calculations were performed to interpret the experimental results. The calculations show fairly good agreement with the experimental results. Isonuclear series for the photoionization of ${\mathrm{Ne}}^{+},$ ${\mathrm{Ne}}^{2+},$ and ${\mathrm{Ne}}^{3+}$ are discussed.

By measuring photoion‐yield spectra for Sr2+ and Sr3+ from Sr+ ions in the ground state, we have determined relative photoionization cross section of Sr+ ions in the energy range from 135–210 eV. The 3d‐ionization of charge‐selected Sr+ ions by photon‐impact was studied for the first time. The yield‐spectrum for Sr2+ has no structure, while that for Sr3+ shows prominent discrete peaks around 140 eV. For the assignment of discrete lines observed, we used a multiconfiguration Dirac‐Fock calculation code. The calculation indicates very strong s−d mixing for the observed peaks. This is understood that after the creation of 3d‐hole, the orbital energy of 4d‐orbital almost coincides with that of 5s‐orbital due to the collapse of the wavefunction.

Multiply charged ions of rare gases were produced through photoionization, using white synchrotron radiation from the accumulation ring of TRISTAN, and the ions were confined in an rf trap. Charge state distribution and lifetime of the stored ions were measured by time-of-flight detection. Confinement of Xe6+-Xe8+ was exhibited with the storage lifetime of several ms, which is limited by the high background pressure needed to accumulate sufficient ion intensity.