Model of the W3(OH) environment based on data for both maser and 'quasi-thermal' methanol lines

In studies of the environment of massive young stellar objects, recent progress in both observations and theory allows a unified treatment of data for maser and 'quasi-thermal' lines. Interferometric maser images provide information on the distribution and kinematics of masing gas on small spatial scales. Observations of multiple masing transitions provide constraints on the physical parameters. Interferometric data on 'quasi-thermal' molecular lines permits an investigation of the overall distribution and kinematics of the molecular gas in the vicinity of young stellar objects, including those which are deeply embedded. Using multiple transitions of different molecules, one can obtain good constraints on the physical and chemical parameters. Combining these data enables the construction of unified models, which take into account spatial scales differing by orders of magnitude. Here we present such a combined analysis of the environment around the ultracompact HII region in W3(OH). This includes the structure of the methanol masing region, physical structure of the near vicinity of W3(OH), detection of new masers in the large-scale shock front and embedded sources in the vicinity of the TW young stellar object.Comment: To appear in the Proceedings of the 2004 European Workshop: "Dense Molecular Gas around Protostars and in Galactic Nuclei", Eds. Y.Hagiwara, W.A.Baan, H.J. van Langevelde, 2004, a special issue of ApSS, Kluwe

Parental melt of the Nadezhdinsky Formation: Geochemistry, petrology and connection with Cu-Ni deposits (Noril'sk area, Russia)

International audienceThe paper addresses genetic relationship between volcanic rocks and ore-bearing intrusions of the Noril'sk area, Siberian Trap Province. Mg-rich rocks were found inside layered the Mikchangdinsky and Ikensky flows at the highest level of the vertical section of a tuff-lava pile in the Nadezhdinsky Formation in the east- ern part of the Noril'sk area. The high La/Sm, Th/U ratios, depletion in Cu, highly radiogenic Sr and unradio- genic Nd isotope compositions suggest their affiliation with the Lower Nadezhdinsky Formation and distinguish them from the Sunduksky layered flow, which has similar internal structure but belongs to the Tuklonsky Formation. The composition of layered Mg-rich basalt flow (the Mikchangdinsky flow) indicates that these rocks likely represent previously unknown parental melt of Nadezhdinsky lavas which are thought to play a crucial role in the genesis of ore mineralisation. Compositionally this melt was significantly different from the parental melt, which formed lavas of the Tuklonsky Formation and this precludes their direct genetic relationship. Olivine composition of the Mikchangdinsky flow indicates rapid depletion of melt by Ni and Cu suggesting early precipitation and fractionation of sulphide melt. Chemical composition and Sr and Nd isotope compositions of rocks from the Mikchangdinsky flow are similar to the Low Talnakh intrusion, while composi- tion of olivine and coexisting spinels manifest significant differences. The compositional differences between the olivine (contents Mn and V) and coexisting spinel (Fe2+/Fe3+ ratios) from the picrite gabbro-dolerites of the Low Talnakh intrusion and picrite of the Mikchangdinsky flow suggest that they may have crystallised from magma of similar composition but at different oxygen fugacity (intrusions being unusually oxidised). The substantial differences in contents of Ca, HREE and Y in olivines from these objects, however, leave open the question of genetic relationship between Nadezhdinsky parental melt and the Low Talnakh intrusion. Although some rocks of the Nadezhdinsky Formation contain unusually low concentrations of chalcophile elements, their role in the ore-forming processes of the Noril'sk district still remains largely uncertain

Study of the structure of the Hoyle state by refractive α-scattering

α + 12C elastic and inelastic to the Hoyle state (0+ 2, 7.65 MeV) differential cross-sections were measured at the energies 60 and 65 MeV with the aim of testing the microscopic wave function [1] widely used in modern structure calculations of 12C. Deep rainbow (Airy) minima were observed in all four curves. The minima in the inelastic angular distributions are shifted to the larger angles relatively those in the elastic ones, which testify the radius enhancement of the Hoyle state. In general, the DWBA calculations failed to reproduce the details of the cross sections in the region of the rainbow minima in the inelastic scattering data. However, by using the phenomenological density with rms radius equal 2.9 fm, we can reproduce the Airy minimum positions.peerReviewe

Conduction band electronic states of ultrathin layers of thiophene/phenylene cooligomers on an oxidized silicon surface

The atomic composition and the electronic properties of the ultrathin vacuum deposited films of the four-unit thiophene/phenylene co-oligomers end-terminated by the -\u421H3 and by the -\u421F3 radicals vacuum deposited onto the oxidized silicon surface were studied using the x-ray photoelectron spectroscopy (XPS) and total current spectroscopy (TCS) techniques. The relative concentrations of the C, S and F atoms measured from the film deposits were evaluated and it was found to correspond to the chemical formulae of the \u421H3-phenylene-thiophene-thiophene-phenylene-\u421H3 (\u421H3-PTTP-\u421H3) and \u421F3-phenylene-thiophene-thiophene-phenylene-\u421F3 (\u421F3-PTTP-\u421F3) molecules studied. The TCS measurements during the increase of the organic layer thickness up to 6 nm on (SiO2)n-Si substrate were used to determine the conduction band peak structure related to the density of the unoccupied electronic states (DOUS) in the range from 5 eV to 22 eV above EF. The theoretical calculations at the B3LYP/6-31G(d)) level were used to determine the DOUS of the two films studied in a broader energy range from 2 eV to 22 eV above EF, which made it possible to determine the position of the lowest unoccupied molecular orbital (LUMO) peak at 4.4 eV in the case of the \u421H3-PTTP-\u421H3 film and at 3.9 eV in the case of the \u421F3-PTTP-\u421F3 film. The effect of the fluorine substitution on the DOUS was determined as approximately 2 eV peak shift towards low electron energies in the case of the \u421F3-PTTP-\u421F3 film compared to the case of the \u421H3-PTTP-\u421H3 film in the electron energy range from 10 eV to 22 eV above EF and as a more complex peak restructuring in the energy range from 5 eV to 10 eV above EF. The DOUS peaks of the two films studied were assigned to have \uf073* character in energy range from 9.5 eV to 22 eV and to have \uf070* character in energy range from 5 eV to 9.5 eV above EF

Formation of epitaxial p-i-n structures on the basis of (In,Fe)Sb and (Ga,Fe)Sb diluted magnetic semiconductors layers

ultilayer structures on the basis of n-type (In,Fe)Sb and p-type (Ga,Fe)Sb diluted magnetic semiconductors (DMS) along with separate (In,Fe)Sb and (Ga,Fe)Sb layers were fabricated on GaAs substrates by pulsed laser sputtering of InSb, GaAs, GaSb, Sb and Fe targets in a vacuum. Transmission electron microscopy and energy-dispersive x-ray spectroscopy reveal a strong dependence of the phase composition of the (In,Fe)Sb compound on the growth temperature. An increase of the latter from 220 °C to 300 °C leads to a coalescence of Fe atoms and formation of a secondary crystalline phase in the (In,Fe)Sb layer with a total Fe content of ≈ 10 at. %. At the same time, the Ga0.8Fe0.2Sb layers obtained at 220 °C and 300 °C are single-phase. The separate In0.8Fe0.2Sb and Ga0.8Fe0.2Sb layers grown on i-GaAs at 220 °C are DMS with Curie temperatures of ≈ 190 K and 170 K, respectively. The three-layer p-i-n diode (In,Fe)Sb/GaAs/(Ga,Fe)Sb structure grown on a GaAs substrate at 220 °C with a Fe content of 10 ± 1 at. % in the single-phase (In,Fe)Sb and (Ga,Fe)Sb layers has a rather high crystalline quality and can be considered as a prototype of a bipolar spintronic device based on Fe-doped III-V semiconductors.publishe

Asymptotic normalization coefficients and halo radii of 12B in the excited states

We present the results of measurements and analysis of the differential cross sections of the 11B(d, p)12B reaction leading to formation of the 1+ ground state and the 0.953-MeV 2+, 1.674-MeV 2−, 2.621-MeV 1−, 2.723-MeV 0+, 3.389-MeV 3− excited states of 12B at Ed = 21.5 MeV. The analysis of the data was carried out within the coupled-reaction-channels method for the direct neutron transfer and the Hauser-Feshbach formalism of the statistical compound-nucleus model. We deduced the spectroscopic factors, asymptotic normalization coefficients, and rms radii of the last neutron in all states studied. The existence of the neutron halos in the 1.674-MeV 2− and 2.621-MeV 1− states was found in consistence with the earlier published data. New information about the enlarged rms radii (6.5 fm) of the last neutron in the unbound 3.389-MeV 3− states of 12B was obtained, which may indicate the evidence of the neutron halo with the orbital momentum of the last neutron equal to two

Asymptotic normalization coefficients and halo radii of 12B in the excited states

We present the results of measurements and analysis of the differential cross sections of the 11B(d, p)12B reaction leading to formation of the 1+ ground state and the 0.953-MeV 2+, 1.674-MeV 2−, 2.621-MeV 1−, 2.723-MeV 0+, 3.389-MeV 3− excited states of 12B at Ed = 21.5 MeV. The analysis of the data was carried out within the coupled-reaction-channels method for the direct neutron transfer and the Hauser-Feshbach formalism of the statistical compound-nucleus model. We deduced the spectroscopic factors, asymptotic normalization coefficients, and rms radii of the last neutron in all states studied. The existence of the neutron halos in the 1.674-MeV 2− and 2.621-MeV 1− states was found in consistence with the earlier published data. New information about the enlarged rms radii (6.5 fm) of the last neutron in the unbound 3.389-MeV 3− states of 12B was obtained, which may indicate the evidence of the neutron halo with the orbital momentum of the last neutron equal to two.peerReviewe