Angular distributions of photoelectrons from both C and O K-shells of the fixed-in-space CO molecule have been measured using the angle-resolved photoelectron-photoion coincidence technique. The measurements have been performed at several photon energies from the ionization thresholds up to about 30 eV above them, where the σ* shape resonances occur. Experimental results are compared with the multiple-scattering calculations of Dill et al (1976 J. Chem. Phys. 65 3158) and with our new calculations in the relaxed-core Hartree-Fock approximation. Our calculations are in a better agreement with the experimental data though numerical discrepancies remain. The experimental angular distributions are fitted by the expansion in Legendre polynomials containing up to ten terms and the extracted parameters are compared with the corresponding theoretical values.

Using the experimental angular distributions of photoelectrons from the K-shells of an oriented CO molecule reported in a companion paper, we have performed a so-called complete experiment and determined 18 dynamical parameters (ten moduli of transition moments and eight phase differences) for the O K-shell, and 16 dynamical parameters (nine moduli of transition moments and seven phase differences) for the C K-shell, and compared them with the results of our calculations in the relaxed-core Hartree-Fock (RCHF) approximation. The agreement between theory and experiment is only qualitative, therefore the model has to be improved by including electron correlations. From the analysis of experimental data we proved that the σ * shape resonance is due to not only the f-wave, as was widely believed earlier, but is due to approximately equal contributions of three partial waves with 1 l 3 for the C K-shell, and four partial waves with 0 l 3 for the O K-shell, with a rather substantial contribution of other partial waves with l 5. From the analysis of the transition moments determined from the experiment it follows that several Cooper minima are likely to exist in partial photoionization cross sections, in particular, in the C 1sσ → εsσ and in the O 1sσ → εdσ transitions.

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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.

Glycosphingolipids are amphipathic compounds consisting of oligosaccharides and ceramide moieties and are cell surface components of all vertebrates. Some glycosphingolipids are tumor-associated antigens and receptors of bacterial toxins and hormones and modulate cell growth and differentiation (1). Some of these biological functions of glycosphingolipids have been elucidated in experiments in which glycosphingolipids are added to cells. However, information on the roles of endogenous glycosphingolipids in biological processes is limited.Endoglycoceramidase (EGCase), 1 found first in a culture supernatant of Rhodococcus sp. strain G-74-2 (2), cleaves the linkage between oligosaccharides and ceramides of various glycosphingolipids. EGCases have been found in bacterial cells (3), earthworms (4), leeches (5), rabbit mammary tissues (6), and clams (7), as well. Three molecular species of the enzyme, EGCases I, II, and III, each with different specificity, have been isolated from the culture supernatant of Rhodococcus sp. strain M-750, a mutant of the wild strain G-74-2 (8). EGCase II hydrolyzed globo-type glycosphingolipids more slowly than did EGCase I. EGCase III specifically hydrolyzed the galactosylceramide linkage of gala-type glycosphingolipids, which were resistant to EGCase I and II. These enzymes are useful in structural studies of glycosphingolipids (7, 9 -14).