New feature in the Auger peak of adsorbed oxygen

Recent joint theoretical and experimental investigations of Auger core-core-valence spectra of alkali adatoms on simple metals have revealed that such technique is capable to ascertain contributions from different adsorption environments in the signal [M.I. Trioni, S. Caravati, G.P. Brivio, L. Floreano, F. Bruno, A. Morgante, Phys. Rev. Lett. 93 (2004) 206802]. Consequently, to verify if such an effect is present also for other chemical species, we study theoretically the KLV transition of oxygen either as a bulk impurity or as an adsorbate in/on Al and Ag (jellium-like). We make use of the Fermi golden rule in which the matrix elements of the interaction are calculated within DFT. We verify that the relevant physical quantity of this phenomenon is the excited local density of states (LDOS), calculated within a region centered on the core ionized atom. The Auger rate for oxygen in Ag bulk displays a single asymmetric peak, while for adsorbed oxygen a second smaller feature at lower energies, and very close to the first one, appears. This unexpected result follows from the removal of the degeneracy of the m quantum number of the 2p states of oxygen at the surface. It is only displayed on the electronically less dense metal (Ag), but not on Al.     

Spectroscopy of the regenerative soot

The mechanisms and processes of the formation of the regenerative soot in a graphite hollow cathode discharge that produces and emits carbon clusters are presented. Mass spectrometry with a specially designed E×B velocity filter analyzes the entire range of the charged clusters from C ₁ to ∼C ₄₃₀₀. The state of the carbon vapour within the source is evaluated by using the characteristic line emissions from the carbonaceous discharge whose formative mechanisms depend upon the kinetic and potential sputtering of the sooted cathode. The carbonaceous discharge generates atomic and ionic C and its clusters C _m (m≥ 2), noble gas metastable atoms and ions, energetic electrons and photons in the cavity of the graphite hollow cathode. The parameters of soot formation and its recycling depend critically on the discharge parameters, the geometry of the hollow cathode and 3D profile of the cusp magnetic field contours. Received 2nd July 2001 and Received in final form 10 September 2001     

Analogues of the Kolosov–Muskhelishvili General Representation Formulas and Cauchy–Riemann Conditions in the Theory of Elastic Mixtures

Analogues of the well-known Kolosov–Muskhelishvili formulas of general representations are obtained for nonhomogeneous equations of statics in the case of the theory of elastic mixtures. It is shown that in this theory the displacement and stress vector components, as well as the stress tensor components, are represented through four arbitrary analytic functions.The usual Cauchy–Riemann conditions are generalized for homogeneous equations of statics in the theory of elastic mixtures.     

Weierstrass Points and Regular Maps

It was shown by G. A. Jones and the first author in [8] that underlying any map on a compact orientable surface S there is a natural complex structure making S into a Riemann surface. In this paper we consider regular maps and enquire about the Weierstrass points on the underlying Riemann surface. We are particularly interested to know when these are geometric, i.e. whether they lie at vertices, face-centres or edge-centres of the map.     

Synthesis, morphology and random laser action of ZnO nanostructures

Three-dimensional (3-D) ZnO random-wall nanostructures and one-dimensional (1-D) ZnO nanorods were prepared on silicon substrates by a simple solid-vapour phase thermal sublimation technique. Optical pumped random lasing has been observed in the ZnO random-wall arrays with a threshold intensity of 0.38 MW/cm² in the emission wavelength from 380 to 395 nm. The optical gain was attributed to the closed-loop scattering and light amplification of the ZnO random-wall. The experimental result suggests that the morphology of nanostructure is the key factor to effect random lasing.     

Growth process of TiC clusters from Ti nanoparticles with evaporated carbon layer

Titanium carbide formation by the solid–solid reaction on the surface of Ti nanoparticles was studied in situ using a high-resolution transmission electron microscope with a heating stage. The cross-sectional image of the Ti surface was clearly observed. Vacuum-deposited carbon covered the whole the surface of Ti nanoparticles in spite of the partly evaporation on the nanoparticle surface. The diffusion of the carbon atoms inside the Ti nanoparticles depended on the size of the nanoparticles. When the Ti nanoparticle diameter was less than 30 nm, carbon atoms diffused into the Ti nanoparticle and formed TiC. The superstructure of the Ti nanoparticles was observed, which revealed the growth process of TiC to be the diffusion of carbon atoms. For Ti nanoparticles with diameter larger than 30 nm it was observed that diffusion of Ti atoms into the carbon layer was dominant, which resulted in formation of TiC in the carbon layer at the surface of Ti nanoparticles.     

Sn/Ge(1 1 1) α-phase: characterization of image resonances by specular electron reflection and selective electron scattering

Image potential resonances on the Sn/Ge(1 1 1) α-phase are investigated by two closely related methods: specular electron reflection and so-called selective electron scattering. Electrons from image resonances are detected on this surface at 120 and 300 K, i.e. below and above the phase transition at about 200 K. The dispersion of the image resonances reveals at these two temperatures equivalent effective electron masses, which are characteristic for this type of electronic surface states. The results of the two methods are consistent according to the similarity of the scattering processes. Changes in the loss peak intensity with the annealing temperature are assigned to the surface quality and are reflected by characteristic photoemission intensities.     

Behavior of zirconium in the ZrOW(100) system at high temperature, studied by ISS, AES and work-function measurements

The behavior of zirconium atoms at the W(100) surface associated with oxygen adsorption at different sample temperatures has been studied by Auger electron spectroscopy (AES), ion scattering spectroscopy (ISS), and the relative change of the work function (Δф) measured by the onset of the secondary electron energy distribution. The results have revealed: (i) adsorption of zirconium onto the W(100) surface followed by the elevation of the sample temperature up to 1710 K in an oxygen partial pressure of 2.7 × 10⁻⁴ induces complete diffusion of zirconium atoms into the W(100) substrate; (ii) further exposure of oxygen induces co-existence of oxygen and tungsten on the surface at 1710 K, resulting in a work function of 4.37 eV; (iii) keeping the sample temperature at 1710 K, simple evacuation of the system has resulted in surface segregation of zirconium atoms to the surface to form a zirconium atomic layer on the top-most surface, reducing the work function to 2.7 eV. The results have revealed that this specific behavior of zirconium atoms at high temperature assures, with very good reproducibility, the highly stable performance and long service life of Zr---O/W(100)-emitters in practical use, even in a low vacuum of 10⁻⁶ Pa.     

Canonical measures on the moduli spaces of compact Riemann surfaces

We study some explicit relations between the canonical line bundle and the Hodge bundle over moduli spaces for low genus. This leads to a natural measure on the moduli space of every genus which is related to the Siegel symplectic metric on Siegel upper half-space as well as to the Hodge metric on the Hodge bundle.     

Clifford分析中的多周期和准多周期Riemann边值问题

本文考虑了R^n 1空间中椭圆函数和准椭圆函数的一些性质，然后分别讨论了周期和准周期Riemann边值问题，给出了解的表达式和可解条件。