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21.
Using integer and noninteger n-Slater type orbitals in single- and double-zeta approximations, the Hartree-Fock-Roothaan calculations were performed for the ground states of first ten cationic members of the isoelectronic series of He atom. All the noninteger parameters and orbital exponents were fully optimized. In the case of noninteger n-Slater type orbitals in double zeta basis sets, the results of calculations obtained are more close to the numerical Hatree-Fock values and the average deviations of our ground state energies do not exceed 2×10-6 hartrees of their numerical results. 相似文献
22.
We report on the development of nanostructured barium titanate (BaTiO3, BT) films on ~200-μm-thick Ag substrates by employing a cathodic electrophoretic deposition (EPD) technique, where solid-state-derived BT nanoparticles are used as the starting material. Structural, morphological and compositional analyses of the as-synthesized BT nanoparticles and films were performed by X-ray diffraction, electron microscopy and energy-dispersive spectroscopy studies. The synthesized nano-BT system has an average crystallite size of ~8.1 nm and a tetragonality (c/a) value ~1.003. To reveal current transport mechanism, the BT films possessing microporous structures and surrounded by homogeneously grown islands were assessed in a metal–insulator–metal (MIM) conformation. The forward current conduction was observed to be purely thermionic up to respective voltages of ~1.4 and 2.2 V as for the fresh and 3-day aged samples. On the other hand, direct tunneling (DT)-mediated Ohmic feature was witnessed at a comparatively higher voltage, beyond which Fowler–Nordheim tunneling (FN) dominates in the respective MIM junctions. The magnitude of current accompanied by FN process was observed to be stronger in reverse biasing than that of forward biasing case. The use of microporous BT films can offer new insights as regards regulated tunneling events meant for miniaturized nanoelectronic elements/components. 相似文献
23.
Using the heavy quark approximation, we have studied the nonleptonic decay mode Λ
b
→Λ
c
a
1. We have included nonfactorizable contributions as well as factorizable ones in our analysis. The estimated branching ratio
for this process is (1.4±0.1)% and the asymmetry parameter α found to be −0.8. 相似文献
24.
Syntheses, characterizations, electrochemistry and catalytic properties for styrene epoxidation of three manganese(III) compounds [MnIIIL1(H2O)(MeOH)](ClO4) (1) [MnIIIL1(N3)(H2O)]·dmf (2) [MnIIIL1(Cl)(H2O)] (3) derived from the Schiff base compartmental ligand N,N′-o-phenylenebis(3-ethoxysalicylaldimine) (H2L1) are reported. The three compounds are characterized by elemental analyses, IR, mass and UV–Vis spectra and conductance values. Single crystal X-ray structures of 1 and 2 have been determined. The structures of 1 and 2 show that these are mononuclear compounds having a salen type structure. In both structures, a dinuclear species is formed by bifurcated hydrogen bonding involving coordinated water molecule. The coordination of chloride in 3 is shown by conductance measurements. The compounds have also been characterized by UV–Vis and mass spectroscopic studies. Cyclic voltammetric and square wave voltammetric studies of the three compounds reveal that these undergo Mn(III)/Mn(II) reduction reversibly with the order of the ease of reduction as 3 > 2 > 1. This order has been explained proposing the composition of active species in solution. Catalytic properties for epoxidation of styrene by all the three complexes using PhIO and NaOCl as oxidant have been studied. The order of both the styrene conversion and styrene epoxidation using the three title compounds is 3 > 1 > 2. Again, it has been observed that more efficient conversion and epoxidation take place when PhIO is used as oxidant. 相似文献
25.
Suchismita Sahoo Rukmani Mohanta 《The European Physical Journal C - Particles and Fields》2017,77(5):344
We study the effect of the scalar leptoquark and \(Z^\prime \) boson on the rare decays of the D mesons involving flavour changing transitions \(c \rightarrow u l^+ l^- (l^{\mp }_i l^{\,\pm \,}_j)\). We constrain the new physics parameter space using the branching ratio of the rare decay mode \(D^0 \rightarrow \mu ^+ \mu ^-\) and the \(D^0 - {\bar{D}}^0\) oscillation data. We compute the branching ratios, forward–backward asymmetry parameters and flat terms in \(D^{+(0)} \rightarrow \pi ^{+(0)} \mu ^+ \mu ^-\) processes using the constrained parameters. The branching ratios of the lepton flavour violating D meson decays, such as \(D^0 \rightarrow \mu e, ~\tau e\) and \(D^{+(0)} \rightarrow \pi ^{+(0)} \mu ^- e^+\) are also investigated. 相似文献
26.
We study the effect of the FCNC mediated Z boson in the rare semileptonic baryonic decays Λb → Λl+l-. We consider the model where the standard model fermion sector is extended by an extra vector-like down quark, as a consequence
of which it allows for CP-violating Z mediated flavor changing neutral current at the tree level. We find that due to this non-universal Zbs coupling, the branching ratios of the rare semileptonic Λb decays are enhanced reasonably from their corresponding standard model values and the zero point of the forward-backward
asymmetry for Λb → Λμ+μ- is shifted to the left.
Received: 2 June 2005, Published online: 26 October 2005
PACS:
13.30.Ce, 12.60.-i, 11.30.Hv 相似文献
27.
We have studied some of the two body nonleptonic decays ofB meson in the context of heavy quark effective theory using factorization hypothesis. Treatinga
1 as a free parameter, we have obtained its value asa
1=0.822±0.045, by correlating the experimental and predicted branching ratio for
process. With this value ofa
1 the branching ratios obtained for other decay channels are in good agreement with the experiment. The decay constant ofD meson is extracted to be 280.82 MeV. Heavy quark spin symmetry has also been tested. 相似文献
28.
29.
ÜMMÜHAN OCAK HALIT KANTEKIN YAŞAR GÖK H. BASIR ŞENTÜRK 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(1-2):87-91
The selective liquid–liquid extraction of various transition metal cations from the aqueous phase to the organic phase was carried out using a 14-membered N2O2S2-macrobicycle. Metal picrates such as Pb2+, Co2+, Zn2+, Ni2+,Cu2+ and Cd2+ were used in this extraction studies. It was found that the ligand showed moderate selectivity towards Pb2+ only among the other metals. The extraction constant (log K
ex) was determined to be 13.8 for Pb2+ complex. 相似文献
30.
Mohanta PK Davis TA Gooch JR Flowers RA 《Journal of the American Chemical Society》2005,127(34):11896-11897
The effect of Ti-based Lewis acids on the reduction of alpha-fluoropropiophenone was examined to determine whether chelation control could be used to direct the diastereoselectivity of conversion to an alpha-fluoro alcohol. Pretreatment of alpha-fluoropropiophenone with TiCl4 followed by reduction with LiBH4 in diethyl ether or methylene chloride provided the syn diastereomer predominantly, while use of Ti(OiPr)4 under identical conditions provided the anti diastereomer as the major product. The products are consistent with a chelation-controlled mechanistic pathway in the former reduction and a nonchelation pathway in the latter case. Detailed 1H, 13C, and 19F NMR studies were consistent with chelation between TiCl4 and alpha-fluoropropiophenone under the reaction conditions utilized in this study. Reduction of other alpha-fluoroketones in the presence of TiCl4 also provided a high degree of diastereoselectivity in the conversion to alpha-fluoro alcohols, showing the generality of this approach. 相似文献