[en] The vibrationally selected CO⁺(A ²Pi/sub i/, v' = 0,1) and CO⁺(B ²Σ⁺, v' = 0,1) ions were generated by the photoionization of CO using Ne and He resonance lamps, respectively. The quenching cross sections of the excited ions were found to be very large and exceed gas kinetic values in the B ²Σ⁺ state. In both excited states it has been observed that the vibrationally excited v' = 1 ion relaxes to v' = 0 level through the collision with the parent CO molecules. The branching ratio of quenching to relaxation in the v' = 1 ions was explained by a cascading relaxation mechanism in which all the vibrational levels underlying the excited v' = 1 level contribute to the energy transfer

No abstract available

[en] Linear and reflectron type time-of-flight (TOF) mass spectrometers were used to study chemical reactions of the core-excited large molecules. A linear TOF mass spectrometer was useful for studying an angle-resolved photofragmentation of the core-excited polyatomic molecule. A reflectron type TOF mass spectrometer was powerful to investigate the site-specific photofragmentation. These mass spectrometers were installed as a part of the endstation of the beamline BL8B1 at UVSOR facility of the Institute for Molecular Science, and some features of them are presented in this paper

[en] Using highly parallel X-ray microbeam of 9 μmx9 μm size and 1.8 arcsec angler divergence obtained by means of successive asymmetric reflections, measurements of the rocking curves of small electric devices was performed. The strain in a local region of LEDs under current operation was investigated. While changing the current, the deviation of the lattice constant around the surface was clearly observed

[en] A scanning hard X-ray microscope using a phase zone plate made of tantalum as its X-ray focusing device is in operation at the Hyogo-BL (BL24XU) of SPring-8. The X-ray microbeam has a size of 0.8 μmx0.7 μm at the photon energy of 10 keV, which can make visible structures as fine as 250-nm line-and-space pattern. The photon flux density at the sample position is ∼2x10⁹ phs/s/μm² and the gain of the phase zone plate is ∼3000. The minimum detection limits irradiated by the microbeam are evaluated to be around 10 ppm for some trace elements contained in standard reference materials of glass matrices. X-ray images obtained so far demonstrate a high feasibility of the microscope

[en] Full text: Total photoabsorption cross sections of CF₃COCH₃ were measured in the C, F and O K-shell regions at the BL-6 beamline of HiSOR facility in Hiroshima University. The observed peaks were tentatively assigned for the first time. The K-shell electrons of F, O and C in the different sites of CO and CF₃ were individually excited into the π* orbital which spreads over the CF₃CO group. The kinetic energies of the CF₃⁺ fragment ions produced were deduced by a peak fitting method. The kinetic energy (KE) distributions of the CF₃⁺ ion have two maxima at 0 eV and 0.45 eV. Relative intensity of the component with low kinetic energy changed from about 10 to 25 and then to 50 percent by sifting excitation site from the F1s of CF₃ to C1s of CO and then to O1s electron. The change of the kinetic energy distribution was reasonably understood by taking account of the F₃C-CO bond dissociation competing in an energy flow from the initially excited K-shell electron to the leaving CF₃ group with vibrational modes which work as an effective intramolecular energy reservoir

[en] A high-resolution monochromator with varied line space plane gratings (VLSG) and spherical focusing mirrors was installed in one of three branches of BL27SU in SPring-8. The performance of the monochromator was roughly evaluated from the photo ion yield of nitrogen molecule. Furthermore, the kinetic energy of the photoelectron from Xe 5p_3/2 orbit was also measured at the same photon energy with the N₂ to avoid the influence of natural width. The resolving power over 10⁴ has been confirmed at the N K-edge

[en] We have designed and constructed the apparatus for the angular distribution measurements of photoejected electrons and ions from free molecules, as a part of the endstation of the c-branch of the beamline BL27SU, a soft X-ray photochemistry beamline at SPring-8. The experimental procedures are described in combination with the use of a capability to switch the horizontal and vertical directions of the linear polarization of the light produced by the figure-8 undulator. As a typical example of the experimental results, we present angle-resolved energetic ion yield spectra in the O 1s excitation region of CO₂

[en] Full text: Studies on the photochemical dynamics of inner-shell excited molecules have been stimulated by the recent advancement of synchrotron radiation technology. Inner-shell excited molecule in a specific vibrational level is produced by means of synchrotron radiation. The yields of fragment ions depend on the vibrational level of the excited molecule. In the present work we studied the kinetic energy distributions of the fragment ions of CF₂CH₂ by exciting the C-H stretching mode in the C K-edge region. The experiments were performed on the beamline BL27SU at the SPring-8 facility. Photoabsorption cross-sections were measured with a resolving power of 9500. Time-of-flight mass spectra were acquired at several photon energies across the two π* peaks. Kinetic energies of the CH₂⁺ and CF₂⁺ fragment ions were deduced by a peak fitting method. Asymmetric peaks observed in 285-286 and 289-290 eV were assigned to the promotion to the π* orbital from the C_H 1s and C_F 1s electrons, respectively. These transitions were accompanied by the C-H stretching progressions. Relative yield of the CH₂⁺ ion with kinetic energy centered near 4 eV increased with the vibrational excitation in the case of the C_F 1s excitation

[en] Full text: Total photoabsorption cross sections of CF₃SF₅, which is a new and potent green- house gas, were measured in the C, F and S K-shell regions. The spectra in the C and F K-edges are the first experimental data. The tentative peak assignments of the K-shell excited CF₃SF₅ were proposed on the basis of comparison with those of CF₄ and SF₆ measured. Site-selective photofragmentation was studied by selectively exciting the K- shell electrons of the C, F and S atoms and the S2p electron. When we excited the C1s and F1s electrons of the CF₃ group, the yields of SF₅⁺ and SF₃⁺ fragment ions were relatively large, and when the F1s electron of SF₅ was excited the relative yield of CF₃⁺ was high. The S1s electron excitation gave a completely different fragmentation pattern, in which the Sⁱs prominent with considerable yields of the multiply charged S²⁺ and S³⁺. The yields of CF₃⁺ and SF₅⁺ were negligible. The S2p excitation gave the similar fragmentation pattern with that of the C1s excitation. That is, hole-dependent fragmentation was strongly observed