How do electronic carriers cross Si-bound alkyl monolayers?

Electron transport through Si-C bound alkyl chains, sandwiched between and Hg, is characterized by two distinct types of barriers, each dominating in a different voltage range. At low voltage, the current depends strongly on temperature but not on molecular length, suggesting transport by thermionic emission over a barrier in the Si. At higher voltage, the current decreases exponentially with molecular length, suggesting transport limited by tunneling through the molecules. The tunnel barrier is estimated, from transport and photoemission data, to be approximately 1.5 eV with a 0.25m(e) effective mass.     

Second-order Møller-Plesset evaluation of the bond length alternation of several series of linear oligomers

We investigate, at the second-order M?ller-Plesset level, the bond length alternation of 30 series of increasingly long linear oligomers for a total of more than 250 compounds, polyacetylene, polymethineimine, polyphosphinoborane, polyaminoborane, polyphosphazene, etc., for which, often for the first time, an accurate estimate of the polymeric bond length alternation is given. The variations induced either by chemical substitution of the backbone atoms or conformational modifications are discussed. Only three polymers present a large bond length alternation (>0.03 A). Systematic basis set effects have been unravelled, i.e., MP2/6-311G(2d) always overshoots the bond length alternation. Best estimates of the bond length alternation are provided for more than a dozen of polymers.     

Negative magnetoresistance in Ba2CoS3

A small negative magnetoresistance and metallic-like behaviour has been detected for the first time in a one-dimensional sulfide containing Co2+.     

Invariant projections and convolution operators

We prove the existence of invariant projections from the Banach space of -pseudomeasures onto with for closed neutral subgroup of a locally compact group . As a main application we obtain that every closed neutral subgroup is a set of -synthesis in and in fact locally -Ditkin in . We also obtain an extension theorem concerning the Fourier algebra.

     

Synthesis,structure and magnetism of homologous series of polycrystalline cobalt alkane mono- and dicarboxylate soaps

Carboxylate-bridged chain complexes of Co(II) (the diaquacobalt(II) mono- and ,-dialkanoates) form two homologous series of layered compounds which have been fully characterised both structurally and magnetically. The crystal structures of two selected members, [Co[CH3(CH2)10COO]2(H2O)2] and [Co[CH3(CH2)18COO]2(H2O)2], have been solved by X-ray powder diffraction and selected-area electron diffraction methods, and refined by the Rietveld technique. Crystal data: monoclinic, P 2(1)/a; a=9.688(1), b=7.5495(9), c=37.281(5) A, =96.70(3) primary, Z=4; and monoclinic, P 2(1)/a; a=9.7260(7), b=7.5477(7), c=57.53(1) A, =94.66(4) primary, Z=4, respectively. Their isomorphous structures contain layers of octahedral diaquacobalt(II) ions bonded to two chemically inequivalent alkanoates, one chelating and one bridging two Co atoms about 6.3 A apart, thus confirming the rare anti-anti conformation mode of the -RCOO groups recently proposed for diaquacobalt(II) ,-dodecanedioate. Extensive magnetic characterisation allowed estimation of the feeble antiferromagnetic coupling, which is weaker in the mono- than in the dialkanoate series.     

Controlling the work function of indium tin oxide: differentiating dipolar from local surface effects

Indium tin oxide (ITO) reacts with tetra(tert-butoxy)tin to give surface bound alkoxytin species. Ligand exchange occurs in these surface bound species by reaction with substituted phenols. The speciation of surface phenoxides was measured in ultrahigh vacuum by X-ray photoelectron spectroscopy, as was the work function for the surface modified ITO. It is shown that the molecular dipole moment of the phenol correlates strongly with the measured ITO work function change; no such correlation exists between the acidity of the phenol and this measured change in work function. Results are consistent therefore with an electrostatic model and not with one involving electronegativities of the ligated phenoxide oxygens.     

The Generalized Multifractional Field: A Nice Tool for the Study of the Generalized Multifractional Brownian Motion

The Generalized Multifractional Brownian Motion (GMBM) is a continuous Gaussian process {X(t)}_{t ? [0,1]}\{X(t)\}_{t\in [0,1]} that extends the classical Fractional Brownian Motion (FBM) and the Multifractional Brownian Motion (MBM) [15, 4, 1, 1]. Its main interest is that, its Hölder regularity can change widely from point to point. In this article we introduce the Generalized Multifractional Field (GMF), a continuous Gaussian field {Y(x,y)}_{(x,y) ? [0,1] ²}\{Y(x,y)\}_{(x,y)\in [0,1]^{\,2}} that satisfies for every tt, X(t)=Y(t,t)X(t)=Y(t,t). Then, we give a wavelet decomposition of YY and using this nice decomposition, we show that YY is b\beta-Hölder in yy, uniformly in xx. Generally speaking this result seems to be quite important for the study of the GMBM. In this article, it will allow us to determine, without any restriction, its pointwise, almost sure, Hölder exponent and to prove that two GMBM's with the same Hölder regularity differ by a "smoother' process.