Photoionization of highly charged ions using an ECR ion source and undulator radiation

Photoionization of Xe4+ to Xe7+ ions was studied by combining an electron cyclotron resonance ion source with synchrotron radiation. Multiconfiguration Dirac-Fock calculations were performed to interpret the data. Many autoionization lines were measured and identified, resulting from excitation of a 4d electron into nf and np orbitals followed by Auger decay of the excited states. Continuum photoionization is negligible for the higher members of the isonuclear series.     

The stereoselective synthesis of C-linked 4′-deoxy aza-disaccharides from C-linked carbo-β-amino acids

The stereoselective synthesis of 4′-deoxy aza-disaccharides in a concise and practical approach is described from C-linked carbo-β-amino acid esters and this protocol utilizes an intramolecular amide bond formation and cis-dihydroxylation for the construction of the new sugar ring.     

Molecular structure and the indirect spin–spin coupling constants in azulene—a proton NMR study in the nematic phase

The proton NMR spectrum of azulene has been investigated in the nematic phase of a liquid crystal. Spectral analysis provided the direct dipole-dipole coupling constants which were used to derive the structural information. It was found that the relative proton-proton distances in the 7- and 5-membered rings deviate significantly from those for regular heptagons and pentagons. Indirect spin-spin couplings were also obtained. Many of the inter-ring and long-range couplings have magnitudes between 0.2–0.8 Hz.     

1H n.m.r. spectra of N-phenylmaleimide in isotropic and nematic phases

¹H n.m.r. spectra of N-phenylmaleimide have been investigated in isotropic as well as nematic phases; the chemical shifts, the direct dipolar and the indirect spin–spin coupling constants have been determined. The direct dipolar coupling constants are consistent with rapidly interconverting energetically equivalent twisted conformations of C₂ symmetry. Under the assumption that only two such conformers are predominantly present, the angle between the phenyl and the maleimide planes is determined as 52.9±0.9°.     

The conformation of (μ-butatriene)hexacarbonyldiiron complex from proton NMR studies in three nematic phases

Proton NMR spectroscopy in three different liquid crystals has been used to determine two conformational angles of (μ-butatriene)hexacarbonyldiiron complex, namely the angle between the two CH₂ planes and the dihedral angle between the two planes containing four carbon atoms of the butatriene moiety. The values are 44 and 46°, respectively. The direct and the indirect geminal HH couplings are shown to be of the same sign in the liquid crystals with positive diamagnetic anisotropy.