Tsuguhisa Sekioka

Correlative multielectron processes in K-shell photoionization of Ca, Ti and V in the energy range of 8-35 keV

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)

High energy resolution PIXE with high efficiency using the heavy ion microbeam

Abstract An X-ray crystal spectrometer using a position sensitive proportional counter combined with tandem microbeam line at Osaka National Research Institute have been developed. This system realizes high energy resolution PIXE analysis using a heavy ion microbeam (E

Photoionization of 4d-electrons in singly charged Xe ions

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.

Chemical state analysis of Cu, Cu2O and CuO with WDX using an ion microbeam

Abstract The possibility of chemical state analysis with a wavelength-dispersive X-ray spectrometer system for particle-induced X-ray emission (WDX-PIXE) using a light ion microbeam is described. High-resolution Cu Lα 1,2 and Lβ 1 X-ray spectra from Cu, Cu 2 O and CuO targets are measured using this spectrometer system. The incident microbeam is focused 2.0 MeV protons with a beam size of 100(H)×30(V) μm 2 . The Cu L X-ray spectra show two clear main peaks and their satellites. The main peaks are the Lα 1,2 and the Lβ 1 diagram lines, respectively. Due to a high detection efficiency of our spectrometer equipped with a position-sensitive detector for soft X-rays, the intensity ratio Lβ 1 /Lα 1,2 is observable, which is the lowest for pure Cu metal, and the largest for CuO. Moreover, the Lα 1,2 X-ray spectrum for CuO shows a large shoulder at the high energy side of the main peak, which is considered to be due to the chemical bonding between Cu and O atoms. The results show that this system can be used for chemical state analysis for various compound materials and for analyzing small areas of materials or small particles.

Storage and Lifetime Measurements of Multiply Charged Ions Produced by Synchrotron Radiation

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.

High energy resolution PIXE analysis using focused MeV heavy ion beams

Abstract The possibility of chemical state microanalysis using high energy resolution PIXE was investigated using a plane crystal spectrometer installed at a heavy ion microbeam line. The spectrometer has the advantage for the analysis of an X-ray spectrum of simultaneously detecting X-rays over an energy range using position sensitive proportional counter without scanning the crystal. Though the detection efficiency is estimated to be at least four orders of magnitude lower than energy dispersive X-ray spectroscopy (EDS) using a Si(Li) detector, the resolution of the system ( d E E ) is better than 10−3, because the effect of beam size on system resolution is negligible. Focused 2 MeV proton and 5 MeV Si3+ ion beams were employed for the analysis of Si Kα X-rays of Si and SiO2. In both cases, it is possible to detect chemical effects by observing relative intensities of X-ray satellite peaks. However, the use of heavy ions is considered to be more promising because the yields of satellite lines using silicon ion bombardment was much higher than that of protons.

Atomic imaging in EBCO superconductor films by an X-ray holography system using a toroidally bent graphite analyzer

X-ray fluorescence holography (XFH) is a new technique enabling the determination of the three-dimensional local atomic structure around a certain element. This method has been applied to analyze the local structure around Cu in 300 nm thin films of EuBa(2)Cu(3)O(7-delta) (EBCO) epitaxially grown on MgO (100) substrate, using the newest system for XFH measurement and high-brilliance synchrotron radiation at SPring-8. Here, the results of a study on the irradiation effect on the local atomic structure of EBCO superconductor with XFH measurements are presented.

Sputtering due to Coulomb explosion in highly charged ion bombardment

Sputtering processes of silicon in the bombardment of highly charged ions (HCIs) are studied using molecular dynamics simulation. Assuming the potential energy of the HCI transferred to target is stored as the electrostatic energy of Si atoms ionized by the HCI, the Si ions up to 375 are embedded on a Si(1 0 0) surface as an initial condition, resulting in Coulomb explosion. The dynamics of particle ejection (sputtering) from the surface and crater formation on the surface are simulated. The formation and propagation of shock wave and rapid increase of the sputtering yield are seen during relaxation process. Strong dependence of the sputtering yield on the HCIs potential energy is found and discussed in comparison with experiment.

The 1s-2p resonance photoionization measurement of O+ ions in comparison with an isoelectronic species Ne3+

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.

4D PHOTOIONIZATION OF SINGLY-CHARGED XE, BA, AND EU IONS

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.