Energy level alignment between C60 and Al using ultraviolet photoelectron spectroscopy

The energy level alignment between C₆₀ and Al has been investigated by using ultraviolet photoelectron spectroscopy. To obtain the interfacial electronic structure between C₆₀ and Al, C₆₀ was deposited on a clean Al substrate in a stepwise manner. The valence-band spectra were measured immediately after each step of C₆₀ deposition without breaking the vacuum. The measured onset of the highest occupied molecular orbital energy level was located at 1.59 eV from the Fermi level of Al. The vacuum level was shifted 0.68 eV toward lower binding energy with additional C₆₀ layers. The observed vacuum level shift means that the interface dipole exists at the interface between C₆₀ and Al. The barrier height of electron injection from Al to C₆₀ is 0.11 eV, which is smaller value than that of hole injection.     

超快光电测量技术

本文综述了近年来趔快光电测量技术的新进展，其中包括扭快光电材料的特性、高速光电器件的基本原理，着重介绍了若干主要的用快光电测量技术．     

Two-dimensional micelle formation of polystyrene-poly(vinylpyridine) diblock copolymers on mice surfaces

We have used atomic force microscopy to study the adsorption of PolyStyrene-Poly(VinylPyridine) (PS-PVP) block copolymers from a selective solvent onto atomically smooth mica surfaces. At certain copolymer concentrations, we observe a highly regular array of spherical surface micelles covering macroscopic areas of the substrate surface. Evidence is given for a thin homogeneous layer underneath the micelles which is probably due to adsorption of free copolymer chains and brush formation prior to the formation of the micellar structures. We discuss the quality of the self-assembled structures regarding different types of defects and try to identify means for improving the long range periodicity of the structures.     

Evidence for the poisson distribution for quasi-energies in the quantum kicked-rotator model

A transformation on the two-dimensional torus which is related to the problem of limit distribution for the distance between the levels in the kicked-rotator model is considered. The first four moments of the r.w. which describe the numbers of visits of a point in a rectangle of measure are calculated. It is shown that when 0 they converge to the first four moments of a Poisson r.w.     

The Büttiker-Landauer model generalized

Büttiker and Landauer studied scattering off an oscillating rectangular barrier in order to shed light on the time aspects of tunneling. The expression for the traversal time resulting from this study is controversial. In addition, doubts have recently been expressed on technical aspects of their work. In an attempt to clarify these issues, we investigate a generalization of their model to arbitrary oscillating barriers,V(x, t)=V ₀(x)+V ₁(x)cos t. In the process, we confirm that Büttiker and Landauer's work is technically sound. However, we show, by several examples, that no direct general relation exists between the characteristic frequency of an oscillating barrier and the duration of the tunneling process. For a wide range of realistic parameters this characteristic frequency does not even exist.This paper is dedicated to E. G. D. Cohen.     

An unusual new reaction of α-olefins with magnesiumn-alkyl derivatives catalyzed by Cp2ZrCl2

The reaction of organomagnesium compounds (OMC) containing alkyl radicals of normal structure with -olefins, resulting in the formation of alkenylorganomagnesium compounds and accompanied by hydride transfer was discovered and systematically investigated. A scheme providing for the formation of zirconacyclopentane complexes was proposed for the mechanism of the reaction.Institute of Organic Chemistry, Ural Branch, Russian Academy of Sciences, 450054 Ufa. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1187–1196, May, 1992.     

Structural and electrochemical studies of annealed LiNiVO4 thin films

We prepared stoichiometric lithium nickel vanadate amorphous thin films by using r.f. magnetron sputtering under controlled oxygen partial pressure. The amorphous films were heated at various temperatures, 300–600 °C, for 8 h. The as‐deposited and annealed thin films were characterized by Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger electron spectroscopy, X‐ray diffraction, scanning electron microscopy and atomic force microscopy. The electrochemical behavior of the various films was studied by the galvanostatic method. The cells were tested in a liquid electrolyte at room temperature, with lithium metal used as the counter and reference electrode. The best electrochemical storage value was obtained with the thin film annealed at 300 °C, which showed superior capacity and small capacity loss during cycling. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of Alkylcyclophosphanes from Red Phosphorus – molecular structure of i-Pr4P4 by gas electron diffraction

A polyphosphide of the type (NaP)_X 1 was obtained from red phosphorus and sodium in presence of small amounts of naphthalene in 1,2-dimethoxyethane as solvent. 1 reacts with alkyl halides in dependence on the kind of alkyl group with formation of different alkylcyclophosphanes. As definite compounds Me₅P₅ 2 , Et₅P₅ 3 (with not definite constitution), i-Pr₄P₄ 4 and t-Bu₄P₄ 5 could be isolated. 1 was identified by X-ray diffraction, 2 – 5 by means of their ¹H, ¹³C, ³¹P n.m.r. and mass spectra. The molecular structure of 4 was identified by electron diffraction.     

Influence of target surface degradation on the properties of r.f. magnetron‐sputtered calcium phosphate coatings

This paper reports a detailed study of how repeated r.f. magnetron sputtering from a hydroxyapatite (HA) powder target affects the nature and reproducibility of a sequential series of thin‐film coatings deposited onto Ti6Al4V substrates. An evaluation of the effective lifespan of the HA sputter targets and the reproducibility of the calcium phosphate (CaP) coatings produced from them has been made from Fourier transform infrared spectroscopy, XPS and, as appropriate, atomic force microscopy and SEM/energy dispersive x‐ray analyses. The annulus region of the target surface, from which sputtering under r.f. magnetron conditions normally occurs, showed severe surface degradation after only one deposition run, as indicated by significant PO₄^3? and OH^? depletion. This deterioration continued after each subsequent deposition cycle but to a much lesser extent than that observed in the initial sputtering period. The layers produced from all of the sputter runs contained the expected Ca²⁺ and PO₄^3? species characteristic of a CaP system but were OH^? deficient in the as‐deposited state. However, the chemical and morphological properties of the coatings did not change significantly until after the third consecutive sputter cycle. Hence, these data indicate that, even though a significant level of degradation of the HA target occurs at the outset of the sputtering procedure, the general plasma conditions employed here have a dominant influence on the coating properties until a critical degradation condition is met. As such, the compacted HA powder targets of interest can have a life‐cycle greater than single usage without detriment to the chemistry and morphology of the coatings produced from them. Copyright © 2003 John Wiley & Sons, Ltd.     

A rigorous control of logarithmic corrections in four-dimensional ϕ4 spin systems

Using Gawedzki and Kupiainen's rigorous block spin transformation method, we study critical phenomena in ⁴ spin systems in four dimensions. In Part I of this work we investigate in detail the renormalization group trajectory of the system not exactly at the critical point.