Multiphonon vibrations at high angular momentum in 182 Os

Evidence is presented for multiphonon excitations based on a high-spin (25 Planck) intrinsic state in the deformed nucleus 182 Os. Angular momentum generation by this mode competes with collective rotation. The experimental data are compared with tilted-axis cranking calculations, supporting the vibrational interpretation. However, the lower experimental energies provide evidence that more complex interactions of states are playing a role.     

Free base meso-tetraaryl-morpholinochlorins and porpholactone from meso-tetraaryl-2,3-dihydroxy-chlorin

meso-Tetraaryl-2,3-dihydroxychlorins (1) were converted in one step to the novel free base macrocycles meso-tetraaryl-2,3-dialkoxy-2a-oxa-2a-homoporphyrins (morpholinochlorins, 3). Their bathochromically shifted chlorin-type UV-vis spectra indicate the presence of a nonplanar chromophore. The structure of meso-tetratolyldiethoxymorpholinochlorin (3b), as determined by X-ray crystallography, was found to be largely planar, suggesting significant conformational flexibility of these macrocycles. Oxidation of diol 1 with MnO(4)(-) generates known porpholactone 4 in high yields. [reaction--see text]     

Generation of azines by the reaction of a nucleophilic carbene with diazoalkanes: a synthetic and crystallographic study

Reactions of the nucleophilic carbene 1,3-dimesityl-imidazol-2-ylidene (1) with diazofluorene, diphenyldiazomethane, and azidotrimethylsilane were examined. Specifically, carbene 1 reacts with diazofluorene and diphenyldiazomethane to give addition products (azines: 3 and 4, respectively). Compounds 3 and 4 were further characterized in the solid-state by single-crystal X-ray crystallographic studies. [3 (a = 9.7936(6) A, b = 10.0529(7) A, c = 16.251(1) A, alpha = 75.765(1) degrees, beta = 79.711(1) degrees, gamma = 64.321(1) degrees, Z = 2, space group P1); 4 (a = 11.681(3) A, b = 11.861(4) A, c = 21.186(3) A, alpha = 90 degrees, beta = 97.05(2) degrees, gamma = 90 degrees, Z = 4, space group P2(1)/n)]. The structural parameters of 3 and 4 are discussed with reference to previously characterized symmetrical and unsymmetrical azines. Structural data suggest that charge separation is possible in 3.     

A homoleptic phosphine adduct of Tl(I)

A homoleptic phosphine adduct of thallium(I) supported by a tris(phosphino)borate ligand has been isolated and structurally characterized.     

High-spin structure of N\simeq Z nuclei around the A = 72 region

High-spin states have been studied in ⁷²Kr and ⁷²Br using the ⁴⁰Ca + ⁴⁰Ca and ³⁶Ar + ⁴⁰Ca reactions at 164 and 145 MeV, respectively. The properties and configurations of the high-spin bands observed have been interpreted using unpaired cranked Nilsson-Strutinsky (CNS), and for ⁷²Kr, paired cranked relativistic Hartree-Bogoliubov (CRHB) calculations. In ⁷²Kr a new band has been identified that has the properties expected for the doubly aligned S-band configuration. In ⁷²Br the previously known bands have been extended to higher spin. This has lead to a re-interpretation of the configurations.Received: 31 October 2002, Published online: 24 February 2004PACS: 21.10.Re Collective levels - 23.20.Lv transitions and level energies - 27.50. + e      

Liquid alumina: detailed atomic coordination determined from neutron diffraction data using empirical potential structure refinement

The neutron scattering structure factor S(N)(Q) for a 40 mg drop of molten alumina (Al2O3) held at 2500 K, using a laser-heated aerodynamic levitation furnace, is measured for the first time. A 1700 atom model of liquid alumina is generated from these data using the technique of empirical potential structural refinement. About 62% of the aluminum sites are 4-fold coordinated, matching the mostly triply coordinated oxygen sites, but some 24% of the aluminum sites are 5-fold coordinated. The octahedral aluminum sites found in crystalline alpha-Al2O3 occur only at the 2% level in liquid alumina.     

A test apparatus for measuring the biaxial strength of brittle materials

Experimental Techniques -     

Zur Analyse der Superphosphate

Ohne Zusammenfassung     

Near-degenerate stereomorphs of the doubly-chiral hcp-{213̅1} surface

The surfaces of hcp crystals can show a variety of structural features and classes of symmetry that differ markedly from those of simpler fcc or bcc crystals. The hcp-{213?1} surface, for example, can occur in four distinct stereomorphs, interconverted by a combination of mirror operations (linking degenerate enantiomorphically related surfaces) and/or the removal of the outermost atomic layer (linking non-degenerate diamorphically related surfaces). The strict pattern of degeneracy amongst these stereomorphs is analogous to that found for molecules with two chiral centres, and hence it is possible to view this system as doubly-chiral. Simple nearest-neighbour bond-counting arguments, however, suggest that for {213?1} even the diamorphically related cases should be near-degenerate, despite the fact that they differ in having either a notably short or notably long interlayer spacing between the outermost layers (ideal spacing ratio 1:5). In the present work, this counterintuitive result is confirmed at the level of density functional theory, both for the ideal and relaxed {213?1} surfaces of Co, Ru and Re.