Selective synthesis of mono-alkyldichlorosilanes via the reaction of olefins with dichlorosilane catalyzed by group VIII metal phosphine complexes

In the hydrosilylation of 1-hexene with dichlorosilane, many phosphine complexes of group VIII metals, Ni, Ru, Rh, PD and Pt, were found to be active catalysts, giving n-hexyldichlorosilane exclusively. Tris(triphenylphosphine)chlororhodium was found to be the most convenient and effective catalyst for the selective synthesis of mono-organodichlorosilanes.     

Thermal annealing and light irradiation effects on hole and electron drift mobilities of Se93.5As6.5 and Se94.3Ge5.7 films

Thermal annealing and light irradiation effects on hole and electron drift mobilities were studied for amorphous Se_93.5As_6.5 and Se_94.3Ge_5.7 films by means of a time-of-flight technique. The electron drift mobility and its activation energy show a drastic increase after the heat and light treatments, while the hole drift mobility remains almost unchanged. The change of electron transport is attributed to a relaxation of local structural distortion, which is correlated with relatively shallow localized states. The present experimental results are inconsistent with the prior proposal that electron transport in amorphous selenides is correlated with Se₈ ring molecules.     

Theory of the mobility of electrons limited by charged impurities in two dimensions

The mobility μ of electrons limited by charged impurities in two dimensions is calculated, based on the proper connected diagram expansion of Kubo's formula. For a Coulomb-type interaction, the Boltzmann relaxation rate is $\text{Γ}{}^{\mathrm{(0)}}\text{= 2}\text{π}{}^2\text{h}\text{?}{}^{\mathrm{?1}}\text{n}{}_{\mathrm{I}}\text{m}{}^1\text{z}{}^2\text{e}{}^4\text{κ}{}^{\mathrm{?2}}\text{p}{}^{\mathrm{?2}}$, where n_I, repr constant. This leads to a mobility proportional to temperature T for non-degenerate electrons. The quasi-particle effect, which is self-consistently contained in the proper connected diagram expansion, yields an equation for the relaxation rate Γ. The solution of this equation yields values in general reduced relative to Γ⁽⁰⁾ at higher densities. The values of μ obtained in our calculations, are higher than those predicted by the Boltzmann theory, and deviations are pronounced at low temperatures.     

Bifurcation phenomena in a free boundary problem for a circulating flow with surface tension

A free boundary problem for a flow around a circle is analyzed. We find and mathematically prove that bifurcations from the trivial flow actually take place. Golubitsky-Schaeffer theory, together with a formula concerning variations of domains, enables us to clarify the behaviors of the branches of nontrivial solutions.     

Gamow-Teller transitions from 58Ni to discrete states of 58Cu

Under the assumption that isospin is a good quantum number, symmetry is expected for the transitions from the ground states of T = 1, T _z = ±1 nuclei to the common excited states of the T _z = 0 nucleus situated between the two nuclei. The symmetry can be studied by comparing the strengths of Gamow-Teller (GT) transitions obtained from a (p, n)-type charge-exchange reaction on a target nucleus with T _z = 1 with those from the β-decay of the T _z = - 1 nucleus. The A = 58 system is the heaviest for which such a comparison is possible. As a part of the symmetry study, we measured the GT transitions from ⁵⁸Ni (T _z = 1) to ⁵⁸Cu (T _z = 0) by using the zero-degree (³ He, t) reaction at 150 MeV/nucleon. With the achieved resolution of 50 keV, many hitherto unresolved GT states have been identified. The GT transition strengths were obtained for states up to 8 MeV excitation, i.e., near to the Q window limitation ( Q _EC = 9.37 MeV) of the β-decay from ⁵⁸Zn (T _z = - 1) to ⁵⁸Cu. The strength distribution is compared with that from shell-model calculations. Received: 24 November 2001 / Accepted: 30 January 2002     

A mimic model of Pt---Rh catalyst prepared by electrochemical deposition of Rh on the Pt(100) surface

Electrochemical deposition of Rh ions on a (5 × 20) Pt(100) surface gave a (1 × 1) LEED pattern with high background intensity. By exposing the (1 × 1) Rh/Pt(100) surface to O₂ or NO, a characteristic p(3 × 1) Rh---O overlayer is built up at about 400 K, which is the same structure observed on the Pt_0.25Rh_0.75(100) surface exposed to NO or O₂. Once the p(3 × 1) Rh---O overlayer is formed, a reversible structural change, ,p(3 × 1) (1 × 1), can be caused at room temperature by adding H₂ and O₂. The p(3 × 1) Rh---O overlayer on the Pt(100) surface may represent a highly efficient catalyst for NO_x reduction.     

Ultra-High Quality Cavity with 1.5 ppm Loss at 1064 nm

Characterization of an ultra-low loss and high finesse Fabry-Perot cavity at 1064 nm is reported. The characteristics are obtained from measurements of cavity decay time, frequency response and transmission efficiency. The results show that the mirrors have the loss of 1.5 ppm including absorption and scattering losses and the reflectance of 99.9873% which corresponds to a cavity finesse of 2.48X10⁴.     

Measurement of density fluctuations on the JIPP T-IIU tokamak via an HCN laser scattering

Observation of density fluctuations in tokamak plasmas is important to study the plasma confinement and to perform high power heating of the plasma. We observed the density fluctuations by means of an HCN laser scattering method during rf heating in the ion-cyclotron range of frequency on a tokamak plasma.The density fluctuations at the drift wave frequency are not enhanced so much by the heating, but the frequency spectrum is shifted to higher frequency. The increase of the density fluctuation level during the heating has been observed only in low-frequency region owing to MHD activity.