Multiply charged Xe ions produced through photoionization of a 3d electron have been measured using the coincidence technique. The coincidence measurement between the energy-selected Auger electron and ions specifies the individual Auger decay channels for the various multiply charged ions. It has been found that only quadruply charged ions are formed through the Auger decays of M45N45N45 type. The M45N23N45 Auger decays predominantly yield Xe5+. These findings indicate that most Xe ions produced through the initial M45 Auger transitions turn into the highest charge state between energetically accessible states through subsequent successive Auger decays. However, in the M45N1N45 and M45N23N23 decays the intensity ratio of Xe5+ with Xe6+ depends on the energy level of the Auger final states. The highly charged ions, Xe7+ and Xe8+, are produced through the initial Auger shake processes from the 3d hole states. Dedicated to the distinguished contributions to soft x-ray photochemistry research by Professor Inosuke Koyano of the Himeji Institute of Technology on the occasion of his 65th birthday.

Multiple-charged Kr ions have been studied using monochromatized synchrotron radiation combined with a coincidence technique. The multiple-charged ions formed through ionization of the inner sub-shells were detected by a time-of-flight mass analyser and the photoelectrons emitted from those orbitals were observed by a cylindrical mirror electron energy analyser. The coincidence measurement between the energy-selected photoelectron and the photoion specified the individual multiple ionization channels of Kr. The Kr 3d ionization produces doubly and triply charged ions. The Kr 3p ionization mainly yields triply charged Kr ions via M23M45N23 Coster–Kronig decays, and the M23M45N1 decays generate considerably quadruply charged ions. The 3s ionization significantly produces quadruply charged ions via super-Coster–Kronig decays with successive Auger transitions.

Total photoabsorption cross section and peak assignments were presented for CF 3 CCH in the carbon K-shell region. Anisotropy parameters of fragment ions obtained by means of an angle-resolved mass spectrometer were helpful to the peak assignments of the K-shell excitation into π* and σ* states.Kinetic energy distributions of the H + , CH + , C 2 H + and CF 2 + fragment ions were fitted using a Gaussian function with one peak, while those of the CF 3 + fragment ion were analyzed by use of two and three components for the C K-shell excitation of the CF 3 and C 2 H sides, respectively. The kinetic energy distribution of the CF 3 + fragment ion was reasonably understood by the consideration that photofragmentation of the K-shell excited molecule probably competes with intramolecular energy relaxation in which the CF 3 group works as an effective energy reservoir. The yields of the CF n + (n = 2,3), C 3 FH 2+ and C 3 F 2 H 2+ ions were dependent on the site of excitation.

Molecular size effects on the site specific photofragmentation of a core excited molecule were investigated by exciting the N and O K-shells for a series of CH3CO(CH2) n CN (n = 0−3) in which the O and N atoms were separated by successively inserting a CH2 group between the two atoms. The photofragment ions coincident with total photoelectrons were observed by means of a reflectron type time-of-flight mass spectrometer. Little difference was observed in the fragmentation patterns between the N and O K-edges in exciting CH3COCN, CH3COCH2CN, and CH3CO(CH2)2CN. Clear discrimination was observed in the long chained CH3CO(CH2)3CN.

We propose a method of spin-parity assignments in decay spectroscopy. Its feasibility was tested for the ␤-delayed neutron decay of spin-polarized 15 B. The ␤-decay asymmetries were measured in coincidence with the delayed neutrons, and the AP values were evaluated for five allowed transitions leading to the excited states in 15 C (E x ϭ3.103, 4.220, 4.657, 5.866, and 6.426 MeV͒. The spin parities of the former three states were uniquely assigned as 1/2 Ϫ , 5/2 Ϫ , and 3/2 Ϫ , respectively. These assignments are consistent with the previous assignments. Because of insufficient statistics for the 5.866-MeV state (1/2 Ϫ), an incorrect assignment (3/2 Ϫ) could not be excluded within the 1 deviation. The spin-parity of the 6.417-MeV state is suggested to be 1/2 Ϫ. The peak analysis with detector response in the neutron time of flight spectra enabled precise determinations of the level energies and widths. The level widths were determined for the first time. The present method is also applicable for ␤-delayed proton, ␣, and ␥ decays, and it can be a powerful tool for spectroscopic studies of nuclei far from the stability.