bluuebunny/crossref_metadata_2025 huggingface dataset:
QUANTUM MOMENT MAPS AND INVARIANTS FOR G-INVARIANT STAR PRODUCTS
Authors: HAMACHI KENTARO
Published: October 2002

We study a quantum moment map and propose an invariant for G-invariant star products on a G-transitive symplectic manifold. We start by describing a new method to construct a quantum moment map for G-invariant star products of Fedosov type. We use it to obtain an invariant that is invariant under G-equivalence. In the last section we give two simple examples of such invariants, which involve non-classical terms and provide new insights into the classification of G-invariant star products.
ERGODIC THEOREMS FOR 2D STATISTICAL HYDRODYNAMICS
Authors: KUKSIN SERGEI B.
Published: October 2002

We consider the 2D Navier–Stokes system, perturbed by a random force, such that sufficiently many of its Fourier modes are excited (e.g. all of them are). We discuss the results on the existence and uniqueness of a stationary measure for this system, obtained in last years, homogeneity of the measures and some their limiting properties. Next we use these results to prove that solutions of the equations obey the central limit theorem and the strong law of large numbers.
GOLD DEPOSITION ON GaAs(001) SURFACES: MOLECULAR-DYNAMICS SIMULATIONS
Authors: ERKOÇ ŞAKIR , AMIROUCHE LYNDA , ROUAIGUIA LEILA
Published: October 2002

We have simulated the gold deposition on arsenic and gallium terminated GaAs(001) surfaces at low and room temperatures. It has been found that gallium terminated surface is relatively less stable in comparison to the arsenic terminated surface. On the other hand, a single gold adatom on the surface has different characteristics than full coverage gold atoms on the surface; a single gold atom diffuses into the surface at room temperature. Simulations have been performed by considering classical molecular-dynamics technique using an empirical many-body potential energy function comprising two- and three-body atomic interactions.
EMERGENCE OF HIERARCHY ON A NETWORK OF COMPLEMENTARY AGENTS
Authors: COPELLI M. , DOS SANTOS R. M. ZORZENON , MARTINS J. S. SÁ
Published: October 2002

Complementarity is one of the main features underlying the interactions in biological and biochemical systems. Inspired by those systems we propose a model for the dynamical evolution of a system composed of agents that interact due to their complementary attributes rather than their similarities. Each agent is represented by a bit-string and has an activity associated to it; the coupling among complementary peers depends on their activity. The connectivity of the system changes in time respecting the constraint of complementarity. We observe the formation of a network of active agents whose stability depends on the rate at which activity of agents diffuses in the system. The model exhibits a nonequilibrium phase transition between the ordered phase, where a stable network is generated, and a disordered phase characterized by the absence of correlation among the agents. The ordered phase exhibits multi-modal distributions of connectivity and activity, indicating a hierarchy of interaction among different populations characterized by different degrees of activity. This model may be used to study the hierarchy observed in social organizations.
DISCRETE WAVELETS AND FILTERING CHAOTIC SIGNALS
Authors: STEEB WILLI-HANS , HARDY YORICK , STOOP RUEDI
Published: October 2002

We study the behavior of one-dimensional chaotic signals and filtering using the discrete Haar wavelet and Daubechies wavelets.
THE FIRST CALCULATION FOR THE MASS OF THE GROUND 4++ GLUEBALL STATE ON LATTICE
Authors: LIU DA QING , WU JI MIN
Published: October 2002

Under the quenched approximation, we perform a lattice calculation for the mass of the ground 4++ glueball state in E++ channel on a D =3 + 1 lattice. Our calculation shows that the mass of this state is MG (4++) = 3.65(6)(18) GeV , which rules out the 4++ or mainly 4++ glueball state interpretation for ξ(2230).
FREE FIELD EQUATIONS FOR SPACE–TIME ALGEBRAS WITH TENSORIAL MOMENTUM
Authors: MANVELYAN R. , MKRTCHYAN R.
Published: October 2002

Free field equations, with various spins, for space–time algebras with second-rank tensor (instead of the usual vector) momentum are constructed. Similar algebras are appearing in superstring/M theories. Special attention is paid to gauge invariance properties, in particular the spin-two equations with gauge invariance are constructed for dimensions 2+2 and 2+4, and the connection with Einstein equation and diffeomorphism invariance is established.
WHEN IS S = A/4?
Authors: CORICHI ALEJANDRO , SUDARSKY DANIEL
Published: October 2002

Black hole entropy and its relation to the horizon area are considered. More precisely, the conditions and specifications that are expected to be required for the assignment of entropy, and the consequences that these expectations have when applied to a black hole are explored. In particular, the following questions are addressed: When do we expect to assign an entropy?; when are entropy and area proportional? and, what is the nature of the horizon? It is concluded that our present understanding of black hole entropy is somewhat incomplete, and some of the relevant issues that should be addressed in pursuing these questions are pointed out.
THE DECAY η'c → ηc ππ
Authors: VOLOSHIN M. B.
Published: October 2002

It is pointed out that the decay of the recently observed charmonium η'c resonance, η'c → ηc ππ is simply related to the well-studied decay ψ′ → J/ψππ and can thus be used for absolute normalization of other decay modes of the η'c. The total rate of the discussed decay should be approximately three to four times the corresponding rate for the ψ′ resonance making the channel with charged pions the most probable exclusive decay mode of the η'c with the branching ratio in the range 5–10%.
COSMOLOGY AND LOCAL PHYSICS
Authors: ELLIS GEORGE F. R.
Published: October 2002

This article considers the two-way relationship between local physics and the large scale structure of the universe - in particular considering Olber's paradox, Mach's principle, and the various arrows of time. Thus the focus is various ways in which local physics is influenced by the universe itself.
LAST ORBITS OF BINARY BLACK HOLES
Authors: GOURGOULHON ÉRIC , GRANDCLÉMENT PHILIPPE , BONAZZOLA SILVANO
Published: October 2002

Binary black hole systems in the pre-coalescence stage are numerically constructed by demanding that the associated spacetime admits a helical Killing vector. Comparison with third order post-Newtonian calculations indicates a rather good agreement until the innermost stable circular orbit.
FERMIONIC CURRENTS ALONG COSMIC STRINGS
Authors: RINGEVAL C.
Published: October 2002

A Yukawa coupling of fermions to the string forming Higgs field leads to the existence of massless1 and massive2,3 fermionic bound states in the vortex that can drastically modify the string dynamics3,4. An exhaustive study of these states is performed. In particular, it is shown that there exists transitions between subsonic and supersonic regimes (i.e. regimes in which the transverse perturbation propagation velocity is less or greater than the longitudinal, sound-like one, respectively), which appear as soon as the massless and massive modes are respectively filled5. This results in modifying the classical stability of cosmic string loops. On the other hand, this confinement mechanism can also be transposed to the the brane context as a viable way for localizing fermions on the brane6.
TIMELESS PROPERTIES FOR QUANTUM COSMOLOGICAL MODELS
Authors: THORWART J. , HALLIWELL J. J.
Published: October 2002

Inspired by the central equation of canonical quantum gravity, the timeless Wheeler-DeWitt equation, we investigate timeless properties for quantum cosmological models. In particular we are interested in the following question: What is the probability of the system entering certain regions of its configuration space without reference to time at all? For the classical case this is a property of the entire system trajectories and can be formulated using a phase space probability distribution 1. In the quantum case we propose and investigate a probability which we obtain by adapting the decoherent histories approach to quantum theory 2 to the timeless case and by using the induced inner product on the physical state space of quantum cosmological models 3. For the example of the Klein-Gordon equation we have investigated the case of space–like surfaces and our results agree with the standard operator methods 4. For a more general model we consider a semiclassical approximation as well as the effect of an environment 1. When the histories are decoherent, the probabilities approximately coincide with the classical case, with the phase space probability distribution replaced by the Wigner function of the quantum state. The influence functional of the environment respects the reparametrization invariance of the quantum cosmological Wheeler-DeWitt equation.
Production of the Bc Meson
Authors: Chen Yu-Qi
Published: October 2002

The production of the Bc and [Formula: see text] mesons was studied in the framework of the factorization formalism and perturbative QCD. Predicted results implied that an observable number of Bc and [Formula: see text] events can be produced at LEP I and at Tevatron. The fragmentation approximation describes the production of the Bc and [Formula: see text] mesons very well in high energy e+ e- collisions. In hadronic collisions, it is valid when and only when the transverse momentum PT of the produced Bc and [Formula: see text] is much larger than the mass of the Bc meson.
New Predictions for Charmed and Bottom Baryons
Authors: Falk Adam F.
Published: October 2002

I review the recent proposal that there are new isotriplet heavy baryons with masses approximately 2380 MeV and 5760 MeV. This prediction follows from the application of heavy spin-flavor and light SU(3) symmetries to the observed charmed and bottom baryon states. It also entails assumptions about the spin and parity quantum numbers of the observed states which are different than is commonly supposed. The discovery of such states would imply that the nonrelativistic constituent quark model is a poor predictor of heavy baryon spectroscopy. I update the analysis in light of new data which have become available.
Novel QCD Effects in the Production and Decay of Quarkonium
Authors: Brodsky Stanley J.
Published: October 2002

There are many outstanding discrepancies comparing the predictions of perturbative QCD and measurements of the rate of production and decay of heavy quark systems. The problems include the J/ψ → ρπ puzzle, leading charmed particle effects, the anomalous behavior of the heavy quark sea components of structure functions, anomalous nuclear target effects, and the large rates observed for single and double quarkonium production at large xF and large pT. I argue that these anomalies may be associated with nonperturbative effects in the higher Fock structure of hadron wavefunctions.
SYNTHESIS AND CHARACTERIZATION OF (CdSe)1-X(ZnS)x MIXED POLYCRYSTALLINE SEMICONDUCTORS BY CO-PRECIPITATION METHOD
Authors: YADAIAH K. , NAYEEM ABDUL , REDDY M. SOMI , NAGABHOOSHANAM M.
Published: October 2002

The polycrystalline (CdSe)1-x (ZnS)x semiconductor powder with (0 ≤ x ≤ 1) has been prepared by controlled co-precipitation method from an alkaline medium using thiourea as a sulphide ion source. Pellets are made out of these powders under 10 tonnes/sq.cm pressure and are sintered at 800°C for 2 hours in nitrogen atmosphere. X-ray studies have indicated that the compounds are polycrystalline in nature with mixed hexagonal structure of CdSe with x = 0-0.3 and cubic structure of ZnS with x = 1. The chemical homogeneity of the samples was observed from the EDAX and also noted that the atomic contents present were as per the constituents taken in the solution. Lattice parameters (a and c) of all the compounds are determined from the X-ray data and are found to decrease with the increase in ZnS content. It is also observed that the grain size decreases with the increase in x from 0-0.6 and later it remained almost the same till x reaches 0.9. Optical studies indicated that the energy gap was as high as 5.2 eV and remained almost same throughout the composition range x = 0-1. Scanning electron micrographs have shown platelet like structure in CdSe and mixed compounds where as a mixed Cubic and Hexagonal structure in ZnS. The results are explained based on different phases present in the compounds.
ENTANGLEMENT-ASSISTED CLASSICAL CAPACITIES OF SOME SINGLE QUBIT QUANTUM NOISY CHANNELS
Authors: LIANG XIAN-TING , FAN HONG-YI
Published: October 2002

In this paper, we calculate the entanglement-assisted classical capacities of the depolarizing channel, the phase damping channel, the phase flip channel, the bit flip channel, the bit-phase flip channel, the two-Pauli channel and the amplitude channel, and discuss the analytical results obtained. The Stokes papametrization representation of a qubit and the characteristic of unitary covariance of some quantum noisy channels are used in the calculations.
RELAXATION AND TRANSIENTS IN A TIME-DEPENDENT LOGISTIC MAP
Authors: LEONEL EDSON D. , DA SILVA J. KAMPHORST LEAL , OLIFFSON KAMPHORST S.
Published: October 2002

We study the one-dimensional logistic map with control parameter perturbed by a small periodic function. In the pure constant case, scaling arguments are used to obtain the exponents related to the relaxation of the trajectories at the exchange of stability, period-doubling and tangent bifurcations. In particular, we evaluate the exponent z which describes the divergence of the relaxation time τ near a bifurcation by the relation τ ~ | R - Rc |-z. Here, R is the control parameter and Rc is its value at the bifurcation. In the time-dependent case new attractors may appear leading to a different bifurcation diagram. Beside these new attractors, complex attractors also arise and are responsible for transients in many trajectories. We obtain, numerically, the exponents that characterize these transients and the relaxation of the trajectories.
EXPERIMENTAL VERIFICATION OF THE BUTTERFLY ATTRACTOR IN A MODIFIED LORENZ SYSTEM
Authors: ÖZOǦUZ S. , ELWAKIL A. S. , KENNEDY M. P.
Published: October 2002

An electronic circuit realization of a modified Lorenz system, which is multiplier-free, is described. The well-known butterfly chaotic attractor is experimentally observed verifying that the proposed modified system does capture the essential dynamics of the original Lorenz system. Furthermore, we clarify that the butterfly attractor is a compound structure obtained by merging together two simple attractors after performing one mirror operation.
ASSOCIATION ANALYSIS OF SOFTWARE MEASURES
Authors: PEDRYCZ W. , SUCCI G. , CHUN M. G.
Published: October 2002

Software measures (metrics) provide software engineers with an important means of quantifying essential features of software products and software processes such as software reliability, maintenance, reusability and alike. Software measures interact between themselves. Some of them may be deemed redundant. Software measures are used to construct detailed prediction models. The objective of this study is to pursue an association analysis of software measures by revealing dependencies (associations) between them. More specifically, the introduced association analysis is carried out at the local level by studying dependencies between information granules of the software measures. This approach is contrasted with a global level such as e.g., regression analysis. We discuss the role of information granules as meaningful conceptual entities that facilitate analysis and give rise to a user-friendly, highly transparent environment.
ON DELETION IN DELAUNAY TRIANGULATIONS
Authors: DEVILLERS OLIVIER
Published: October 2002

This paper presents how the space of spheres and shelling may be used to delete a point from a d-dimensional triangulation efficiently. In dimension two, if k is the degree of the deleted vertex, the complexity is O(k log k), but we notice that this number only applies to low cost operations, while time consuming computations are only done a linear number of times.

This algorithm may be viewed as a variation of Heller's algorithm,1,2 which is popular in the geographic information system community. Unfortunately, Heller algorithm is false, as explained in this paper.
AN OPTIMAL MORPHING BETWEEN POLYLINES
Authors: BESPAMYATNIKH SERGEI
Published: October 2002

We address the problem of continuously transforming or morphing one simple polyline into another so that every point p of the initial polyline moves to a point q of the final polyline using the geodesic shortest path from p to q. We optimize the width of the morphing, that is, the longest path made by a point on the polyline. We present an algorithm for finding the minimum width morphing in O(n2) time using O(n) space, where n is the total number of vertices of polylines. This improves the previous algorithm7 by a factor of log 2 n.
ON TWO-PHASE FLOW IN FRACTURED MEDIA
Authors: YEH LI-MING
Published: October 2002

A model describing two-phase, incompressible, immiscible flow in fractured media is discussed. A fractured medium is regarded as a porous medium consisting of two superimposed continua, a continuous fracture system and a discontinuous system of medium-sized matrix blocks. Transport of fluids through the medium is primarily within the fracture system. No flow is allowed between blocks, and only matrix-fracture flow is possible. Matrix block system plays the role of a global source distributed over the entire medium. Two-phase flow in a fractured medium is strongly related to phase mobilities and capillary pressures. In this work, four relations for these functions are presented, and the existence of weak solutions under each relation will also be shown.
LOCAL AND GLOBAL EXISTENCE OF SOLUTIONS TO EQUATIONS FOR FLOWS OF FIBRE SUSPENSIONS
Authors: MUNGANGA J. M. W. , REDDY B. D.
Published: October 2002

We establish the existence and uniqueness, locally and globally in time, of solutions to the governing equations for fibre suspension flows, for sufficiently small data. The linear and quadratic closure rules are considered, and the rotary diffusivity is assumed to be constant. The existence of a unique classical solution, local in time, is proven for the cases of both linear and quadratic closure rules. By restricting consideration to the physically significant case of constant rotary diffusivity it is possible to obtain the first results on global existence for this problem. In particular, the existence and uniqueness of a classical solution, globally in time, is established for sufficiently small data. The solution is shown to be stable in the absence of a body force. Existence and uniqueness of solutions to the steady problem are also established.
BULK VISCOUS ANISOTROPIC COSMOLOGICAL MODELS WITH VARIABLE G AND Λ
Authors: PRADHAN ANIRUDH , YADAV VINOD KUMAR
Published: October 2002

The Einstein field equations with bulk viscosity and variable G and Λ for Bianchi-type universes are studied under the assumption of a power-law time variation of the expansion factor, achieved via a suitable power-law assumption for the Hubble parameter suggested by M. S. Berman. All the models have a power-law variation of pressure and density and are singular at the epoch t = 0. The variation of G(t) as [Formula: see text] and Λ(t) as [Formula: see text] is consistent with these models.
ELECTRICAL CONDUCTIVITY AT THE CORE OF A MAGNETAR
Authors: GHOSH SUTAPA , GOSWAMI KANUPRIYA , CHAKRABARTY SOMENATH , GOYAL ASHOK , GHOSH SANCHAYITA
Published: October 2002

An expression for the electrical conductivity at the core of a magnetar is derived using Boltzmann kinetic equation with the relaxation time approximation. The rates for the relevant scattering processes, e.g., electron–electron and electron–proton scattering processes are evaluated in presence of strong quantizing magnetic fields using tree level diagrams. It is found that in the presence of a strong quantizing magnetic field, electrical conductivity behaves like a second rank tensor. However, if the zeroth Landau levels are only level occupied by the charged particles, it again behaves like a scalar of a one-dimensional system.
GENERAL ENTROPY OF GENERAL MEASURES
Authors: DUKHOVNY ALEXANDER
Published: October 2002

The concept of entropy is an important part of the theory of additive measures. In this paper, a definition of entropy is introduced for general (not necessarily additive) measures as the infinum of the Shannon entropies of "subordinate" additive measures. Several properties of the general entropy are discussed and proved. Some of the properties require that the measure belongs to the class of so-called "equientropic" general measures introduced and studied in this paper. The definition of general entropy is extended to the countable case for which a sufficient condition of convergence is proved. We introduce a method of "conditional combination" of general measures and prove that in that case the general entropy possesses the "subset independence" property.
SPECTROMICROSCOPY OF BIOLOGICAL AND ENVIRONMENTAL SYSTEMS AT STONY BROOK: INSTRUMENTATION AND ANALYSIS
Authors: JACOBSEN C. , BEETZ T. , FESER M. , OSANNA A. , STEIN A. , WIRICK S.
Published: October 2002

Soft X-ray microscopy allows one to study nanoscale heterogeneities in dry and wet environmental science, biological, polymer, and geochemical specimens. Recent advances in instrumentation at the X-1A beamline at the National Synchrotron Light Source at Brookhaven National Laboratory are described. Spectromicroscopy data analysis methods including component mapping and principal component analysis (PCA) are then discussed.
THE SCANNING X-RAY MICROPROBE AT THE ESRF "X-RAY MICROSCOPY" BEAMLINE
Authors: SUSINI J. , SALOMÉ M. , FAYARD B. , ORTEGA R. , KAULICH B.
Published: October 2002

The development of high brilliance X-ray sources coupled with advances in manufacturing technologies of focusing optics has led to significant improvements in submicrometer probes for spectroscopy, diffraction and imaging applications. For instance, X-ray microscopy in the 1–10 keV energy range is better-suited for analyzing trace elements in fluorescence yield. This article will be biased towards submicron fluorescence microscopy developed on the ID21 beamline at the ESRF. The main technical developments, involving new focusing lenses or novel phase contrast method, are presented. Strengths and weaknesses of X-ray microscopy and spectromicroscopy techniques are discussed and illustrated by examples in biology, materials science and geology.
RESONANT AUGER SPECTRA OF Kr NEAR THE L3 THRESHOLD
Authors: IBUKI T. , OKADA K. , KAMIMORI K. , SASAKI J. , YOSHIDA H. , HIRAYA A. , SUZUKI I. H. , SAITO N. , NAGAOKA S. , SHIMIZU Y. , OHASHI H. , TAMENORI Y.
Published: October 2002

Auger electron spectra were studied by scanning the photon energy near the L 3 threshold of krypton. Two resonant transitions were observed in the photon energy region 1673–1678 eV for the first time. They were identified to be the resonant 3d -2 5s and 3d -2 4d states originating in the 2p 3/2-1 5s and 2p 3/2-1 4d excitations, respectively.
DETERMINATION OF THE FIRST DISSOCIATIVE IONISATION ENERGY OF POLYATOMIC MOLECULES BY THRESHOLD PHOTOELECTRON PHOTOION COINCIDENCE (TPEPICO) SPECTROSCOPY: APPLICATION TO CF4, SF6, SeF6, TeF6 and SF5CF3
Authors: CHIM R. Y. L. , KENNEDY R. A. , TUCKETT R. P. , ZHOU WEIDONG , JARVIS G. K. , MAYHEW C. A. , COLLINS D. J. , HATHERLY P. A.
Published: October 2002

A recent paper (Science2000, 289, 611) has suggested that an anthropogenic greenhouse gas, SF 5 CF 3, recently detected in the atmosphere, has the highest radiative forcing of any gas-phase molecule. The ground state of [Formula: see text] is repulsive in the Franck–Condon region, the parent ion is not observed, and the onset of ionisation can only give an upper limit to the energy of the first dissociative ionisation pathway of [Formula: see text]. Using a variation of threshold photoelectron photoion spectroscopy, we have determined the kinetic energy released into the two fragments over a range of energies. Using an impulsive model, the data has been extrapolated to zero kinetic energy to obtain a value for the first dissociative ionisation energy for SF 5 CF 3 of 12.9 ± 0.4 eV. The enthalpy of formation at 0 K of SF 5 CF 3 is determined to be -1770 ± 47 kJ mol -1, and the dissociation energy of the SF 5– CF 3 bond at 0 K to be 392 ± 48 kJ mol -1 or 4.06 ± 0.45 eV. The implication of this bond strength is that SF 5 CF 3 is very unlikely to be broken down by UV radiation in the stratosphere. A similar experiment for [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] yielded values for their dissociative ionisation energies of 14.45 ± 0.20, 13.6 ± 0.1, 14.1 ± 0.5 and 14.5 ± 0.6 eV, respectively. The first two results agree with previous data on the CF 3 and SF 5 free radicals. The final two results yield 0 K enthalpies of formation of [Formula: see text] and [Formula: see text] to be 166 ± 52 and 4 ± 62 kJ mol -1, respectively.
ABSORPTION SPECTRUM OF OZONE IN THE 105–200 NM WAVELENGTH REGION
Authors: TU S. J. , NEE J. B.
Published: October 2002

Excited states of ozone are investigated based on the absorption spectrum measured in the wavelength region 105–200 nm. Two Rydberg series corresponding to the transition 6a 1 → ns, np and 4b 2 → ns and np were assigned for the most of the strong peaks in the absorption spectrum. In 112–105 nm wavelengths, the progression of vibrational bands with an energy spacing of about 622 cm -1 was measured which was unknown before.
SINGLE-PHOTON IONIZATION OF THE PRIMARY PHOTOFRAGMENTS OF CHLORINE MONOXIDE
Authors: FLESCH R. , PLENGE J. , SCHÜRMANN M.-C. , KÜHL S. , KLUSMANN M. , RÜHL E.
Published: October 2002

The single-photon ionization mass spectrometry of primary photofragments of chlorine monoxide (ClO) is reported. The use of laser-produced plasma (LPP) radiation in pump–probe experiments allows us to ionize the laser-generated atomic photoproducts with tunable radiation in the vacuum ultraviolet regime (E = 10–18 eV). Autoionization resonances of the atomic photoproducts are used to establish the quantum states of the photoproducts and to enhance the detection sensitivity. Predissociation and direct dissociation of A (2Π)-excited ClO yields Cl (2 P )+ O (3 P ) as well as Cl (2 P )+ O (1 D ), respectively. The quantum yield of O (1 D ) formation is reported in the threshold regime near the ClO [ A (2Π)] dissociation limit.
CONTROL OF EXCITONIC AND ELECTRON–HOLE PROCESSES IN WIDE-GAP CRYSTALS BY MEANS OF ELASTIC UNIAXIAL STRESS
Authors: LUSHCHIK A. , LUSHCHIK CH. , VASIL'CHENKO E. , KIRM M. , MARTINSON I.
Published: October 2002

The time-resolved emission spectra and the excitation spectra of the main emissions have been measured for the first time in stressed and unstressed RbI crystals using synchrotron radiation of 10–30 eV at 8 K. It has been shown that the applied elastic uniaxial stress (EUS) offers promise for the separation of the elementary multiplication mechanisms of electronic excitations. A different influence of EUS on the self-trapping of excitons or holes at 8 K has been discussed. The mean free path of free excitons decreases, while that of valence holes increases in a stressed RbI crystal.
THERMALLY ASSISTED EMISSION OF ELECTRONS AND VUV PHOTONS FROM IRRADIATED RARE GAS SOLIDS
Authors: SAVCHENKO E. V. , GRIGORASHCHENKO O. N. , OGURTSOV A. N. , RUDENKOV V. V. , GUMENCHUK G. B. , LORENZ M. , SMITH-GICKLHORN A. M. , FRANKOWSKI M. , BONDYBEY V. E.
Published: October 2002

Relaxation processes and stability of charge centers in preirradiated doped rare gas solids were studied combining spectrally resolved thermally stimulated luminescence (TSL) and exoelectron emission (TSEE) techniques. The thermally assisted emission of electrons was found. Comparison of the yields of electrons and photons in VUV and visible ranges made it possible for the first time to discriminate between reactions of neutral species and charge carriers and find their interconnection. Ranges of charge center thermostability were found.
DOMAIN IMAGING OF MESOSCOPIC MAGNETIC STRUCTURES BY PHOTOELECTRON EMISSION MICROSCOPY
Authors: KIWATA H. , KIHARA T. , ONO K. , OSHIMA M. , OKUDA T. , HARASAWA A. , KINOSHITA T. , YOKOO A.
Published: October 2002

We have observed magnetic domains of mesoscopic magnetic structures of Ni by synchrotron radiation photoelectron emission microscopy using circularly polarized soft X-rays from the bending magnet. The mesoscopic magnetic structures of Ni were fabricated by electron beam lithography combined with a chemical liftoff process. The geometries of the Ni mesoscopic samples were square, triangular and hexagonal with the sizes of 5 and 10 μm. The magnetic domains structures were clearly observed by dividing the images measured at the Ni L3-edge by the images measured at the Ni L2-edge. The magnetic domains of the Ni mesoscopic structures are discussed with the results of magnetic force microscopy and micromagnetic simulation.
MORPHOLOGY AND CHEMISTRY OF S-TREATED GaAs(001) SURFACES
Authors: HEUN S. , GREGORATTI L. , BARINOV A. , KAULICH B. , RUDOLF M. , LAZZARINO M. , BIASIOL G. , BONANNI B. , SORBA L.
Published: October 2002

The morphology and chemistry of S-treated GaAs(001) surfaces have been investigated by using an atomic force microscope (AFM) and a synchrotron radiation scanning photoemission microscope (SPEM) for a sample (A) which was directly blown dry with N 2 after the S-treatment and for another sample (B) which was rinsed by DI water and finally blown dry with N 2 after the S-treatment. AFM and SPEM images show for sample A a very inhomogeneous surface morphology, while the surface morphology of sample B appeared to be very homogeneous. On the surface of sample A, an inhomogeneous distribution of particles was observed by AFM. Nearly all these particles could be removed by the water rinse. Laterally resolved core level spectra analysis shows that on both samples the S bonds mainly to Ga. Only traces of As–S and As–As bonds exist at the sample surface while no S–S bonds could be detected. From the analysis of the O 1s core level it can be deduced that only a small GaAs surface fraction is oxidized. Furthermore, O–S bonds are present at the surface. On the sample before the water rinse, the number of O–S bonds is laterally inhomogeneously distributed. The number of O–S bonds can be drastically reduced by the water rinse, which also results in a homogeneous distribution of those bonds. We deduce that the O–S bonds belong to sulfate SO x deposits at the sample surface which are the particles that were imaged by AFM.
THE EFFECT OF A LiF LAYER ON Al/LiF/Alq3 INTERFACES STUDIED WITH ELECTRON SPECTROSCOPIES
Authors: YOKOYAMA TAKAHIRO , ISHII HISAO , OUCHI YUKIO , YOSHIMURA DAISUKE , SEKI KAZUHIKO , ITO EISUKE , OJI HIROSHI
Published: October 2002

The interface of the tris (8-hydroxyquinoline) aluminum ( Alq 3)/ LiF/Al system was investigated with ultraviolet photoelectron spectroscopy (UPS), metastable atom electron spectroscopy (MAES), and X-ray photoelectron spectroscopy (XPS). Strong chemical interaction was observed at Alq 3 on Al interface. By inserting a LiF layer, this interaction is suppressed and interface energy level alignment is changed to reduce a barrier for electron injection. The enhancement of device efficiency is ascribed to these phenomena. The importance of the combined use of various techniques on the same interface is stressed.
DEPTH-RESOLVED SOFT X-RAY EMISSION SPECTROSCOPY OF Si-BASED MATERIALS
Authors: ZIMINA A. V. , SHULAKOV A. S. , EISEBITT S. , EBERHARDT W.
Published: October 2002

We discuss a soft X-ray emission (SXE) valence band (VB) spectroscopy method for the study of the electronic structure and chemical phase composition of solids in a near-surface region with depth resolution. The depth information is obtained by variation of the energy of the incident electron beam used to excite the SXE spectra. As the information depth can be varied from about 1 nm to 1 μm in silicon, this method is suitable for the investigation of materials of modern micro- and nanoelectronics. VB → core level (Si 2p or Al 2p) transitions in Si-based materials are used to demonstrate the technique. It was found that the contribution of the signal from the near-surface region (< 1.5 nm) can be substantial (up to 50%) when the primary electron energy does not exceed the Si L 2,3 threshold by more than 150 eV. The technique is applied to Al impurities in a Si matrix, produced by ion implantation. The electronic structure at the Al sites and depth distribution of the Al impurity change markedly after postimplantation annealing. The observed electronic structure after annealing is in agreement with electronic structure calculations for substitutional Al impurities in a crystalline Si lattice.
HIGH-RESOLUTION AND LOW-TEMPERATURE PHOTOEMISSION SPECTROSCOPY AT THE HISOR HELICAL-UNDULATOR BEAMLINE
Authors: ARITA MASASHI , SHIMADA KENYA , NAMATAME HIROFUMI , TANIGUCHI MASAKI
Published: October 2002

We report an experimental system dedicated for high-resolution and low-temperature photoemission spectroscopy installed on the helical-undulator beamline of a compact 700 MeV electron-storage ring (HiSOR) at Hiroshima University. A 3 m off-plane Eagle normal-incidence monochromator at the beamline covers the photon-energy range of hν = 4–40 eV. From the photoemission spectra near the Fermi edge of evaporated Au film, the total energy resolution was estimated to be 4.5 and 7.5 meV at hν = 7.1 and 22.6 eV, respectively. We have also performed photoemission measurements of Yb metal, which demonstrated highly bulk-sensitive spectra for the excitation by low energy photon. The high-resolution photoemission spectra of Y 1 - x Ca x TiO 3 with x = 0.41 in the vicinity of the boundary between the metallic and insulating phases exhibited anomalous temperature dependence in comparison with those of normal metals.
DEVELOPMENT OF A CONICAL ENERGY ANALYZER FOR ANGLE-RESOLVED PHOTOELECTRON SPECTROSCOPY
Authors: IWASAKI KOTA , MITSUKE KOICHIRO
Published: October 2002

A new angle-resolving electron energy analyzer composed of a conical electrostatic prism and a position-sensitive detector was developed for gas phase photoelectron spectroscopy. The performance of the analyzer has been tested by measuring photoelectron spectra of Ar using a helium discharge lamp. The angular resolution of 3° was achieved at the pass energy E of 5.6 eV. The best energy resolution was ΔE/E = 0.043 at E = 1.4 eV .
PHOTOELECTRON SPECTROSCOPY STUDY OF AMMONIA ADSORPTION ON ${\rm ZnO}(10\bar 10)$
Authors: OZAWA KENICHI , EDAMOTO KAZUYUKI
Published: October 2002

Ammonia adsorption on the nonpolar [Formula: see text] surface has been studied using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. Ammonia adsorbs on the surface molecularly at room temperature. Adsorption induces the shift of the O 2p dangling bond state to the higher binding energy side. This implies the formation of the hydrogen bond between the surface O atoms and the H atoms of NH 3. Annealing the ammonia-covered surface induces the partially decomposed NH x (x=1,2) species. All adsorbates are removed at the surface temperature of 625–650 K. When the surface is precovered with K, no adsorbed ammonia is observed. Not only a site blocking effect but also a nonlocal effect for poisoning is proposed.
BURIED INTERFACES OF HEAT-LOADED Mo/Si MULTILAYERS STUDIED BY SOFT-X-RAY EMISSION SPECTROSCOPY
Authors: MIYATA N. , IMAZONO T. , ISHIKAWA S. , ARAI A. , YANAGIHARA M. , WATANABE M.
Published: October 2002

We measured Si L2,3 soft-X-ray emission spectra from Mo/Si multilayers annealed at 400°C. We showed that MoSi 2 was formed at the interface, and the thickness of the MoSi 2 interlayer increased with the annealing time. By an analysis of the soft-X-ray emission spectra and the patterns of small-angle X-ray diffraction, we estimated the thickness of the MoSi 2 interlayer and a diffusion coefficient between Mo and Si at 400°C as 1.1 (± 0.2) × 10-18 cm 2/ s . We showed that soft-X-ray emission spectroscopy is a useful tool for studying the thermal change of the buried interface nondestructively.
A FOURIER TRANSFORM SPECTROMETER WITHOUT BEAM SPLITTER FOR THE VUV–EUV RANGE
Authors: DE OLIVEIRA NELSON , JOYEUX DENIS , PHALIPPOU DANIEL , POLACK FRANCOIS
Published: October 2002

We describe a Fourier transform spectrometer designed to operate down to 60 nm on a synchrotron beam line. As far as we know, there is no such instrument available in the EUV (λ < 140 nm) partly because manufacturing accurate beam splitters remains the major difficulty at these wavelengths. We use a wave front division interferometer instead of an amplitude division one to overcome this difficulty. The interferometer is based on a modified Fresnel bimirror configuration, which is controlled by an original optical system. This system keeps the mirror tilt error to a negligible value during mirror translation, and provides a sensitive interferometric measurement of the mirror translation. The sampling interval is 29 nm (path difference), allowing one to record large band spectra down to λ = 58 nm with spectral resolution δσ = 0.33 cm -1 for 512 K samples (one-sided interferograms).

We measured the apparatus function by recording an interferogram from a He–Ne stabilized laser. By studying the white noise in the corresponding spectrum, we found that the sampling error in the interferogram was about 0.4 nm rms, which produces a near-perfect apparatus function. Finally, we recorded the visible/near UV spectrum of an arc mercury lamp for illustration.
VUV SPECTROSCOPY OF CRYSTALLINE EMITTERS BASED ON 5d–4f TRANSITIONS IN RARE EARTH IONS
Authors: MAKHOV V. N. , KIRIKOVA N. YU. , KHAIDUKOV N. M. , KIRM M. , NEGODIN E. , ZIMMERER G. , LAM S. K. , LO D. , KRUPA J. C. , GESLAND J. Y.
Published: October 2002

The spectroscopic properties of several fluoride crystals ( LiYF 4, KYF 4, K 2 YF 5, KLiYF 5, CsY 2 F 7, SrF 2) doped with Nd 3+, Er 3+ or Tm 3+ are analyzed from the viewpoint of their possible applications as active media for VUV solid state lasers. It has been found that in many crystals there exists very efficient nonradiative relaxation from higher-lying 5d states to the lowest 5d level responsible for the spin-forbidden luminescence. In fact, the energy level diagram of 5d–4f transitions for these two ions represents a typical four-level laser scheme with a considerably larger Stokes shift of 5d–4f luminescence from the edge of the strong spin-allowed 4f–5d absorption than for Nd 3+, which causes smaller reabsorption of emitted VUV radiation in the crystals doped with Er 3+ or Tm 3+. Two crystals LiYF 4: Nd 3+ and SrF 2: Er 3+ were tested for laser action under pumping by a pulsed F 2 laser operating at 157 nm. However, no indications of the appearance of stimulated emission have been detected for both crystals. The possible reasons for the absence of lasing are discussed.
A TEMPERATURE-PROGRAMMED X-RAY PHOTOELECTRON SPECTROSCOPY STUDY OF THE DECOMPOSITION REACTIONS OF UNSATURATED HYDROCARBONS ON Ni(100)
Authors: WHELAN CAROLINE M. , NEUBAUER RALF , DENECKE REINHARD , STEINRÜCK HANS-PETER
Published: October 2002

We present a temperature-programmed X-ray photoelectron spectroscopy study of the thermal chemistry of acetylene, ethylene and propene on Ni(100) using synchrotron radiation. The use of a third generation light source makes it possible to measure high resolution photoemission spectra within a few seconds approaching the ideal of real-time analysis. The evolution of the C 1s core level spectra has been monitored in situ as a function of sample temperature from 90 to 530 K. Analysis of binding energies and changes in intensities and correlation with previous data from the literature have allowed us to distinguish the surface intermediates formed during the thermal reactions. The resultant temperature-dependent intensity curves clarify the dehydrogenation mechanisms of acetylene and ethylene and provide new insight into the decomposition of propene.
THE EXPLOITATION OF MULTICHANNEL DETECTION IN SCANNING PHOTOEMISSION MICROSCOPY
Authors: POTTS A. W. , MORRISON G. R. , GREGORATTI L. , BARINOV A. , KAULICH B. , KISKINOVA M.
Published: October 2002

Sub-micrometer resolution has been achieved in photoemission microscopy thanks to the high flux and brightness of the soft X-rays provided by third generation synchrotron sources and the progress in microfabrication of focusing elements. The use of multichannel detectors in recently constructed scanning microscopes adds speed and flexibility in data acquisition. Here we present preliminary results on a study of the interactions between sub-monolayer Pd and polycrystalline Ni obtained with the scanning photoemission microscope at Elettra to illustrate the importance of multichannel data acquisition in photoemission microscopy.
MAGNETIC CIRCULAR DICHROISM OF 4d–4f RESONANT X-RAY EMISSION FOR GADOLINIUM AND TERBIUM
Authors: TAKAYAMA YASUHIRO , OHTSUBO HIDEO , SHINODA MOTOKI , OBU KENJI , LEE CHOL , SHIOZAWA HIDETSUGU , ISHII HIROYOSHI , MIYAHARA TSUNEAKI , OKAMOTO JUN
Published: October 2002

We have measured the magnetic circular dichroism (MCD) of X-ray emission spectra (XES) for gadolinium and terbium in the 4d–4f resonant excitation region. Clear MCD signals in the XES were observed and they dramatically changed as the excitation energy changed. Especially, an extremely large MCD signal appeared with the 8D resonant excitation for gadolinium. Comparison between the MCD for XES and total photoelectron yield (TEY) shows that the XES are very insensitive to the surface state. As a result, the measurement of XES was proved to be a superior technique for estimating the genuine magnetic moment in the bulk.
TRANSVERSE MAGNETO-OPTICAL KERR EFFECT IN THE SOFT X-RAY REGIME OF ULTRATHIN IRON FILMS AND ISLANDS ON W(110)
Authors: SENZ V. , KLEIBERT A. , BANSMANN J.
Published: October 2002

The transverse magneto-optical Kerr effect (T-MOKE) in the soft X-ray regime is used to investigate the magnetic properties of ultrathin epitaxial Fe(110) films and thermally created epitaxial Fe islands on W(110). The measurements have been carried out at the Fe 2p core levels with tunable, linearly polarized synchrotron radiation. Besides the chemical selectivity T-MOKE at core levels is characterized by a much larger sensitivity compared to the visible regime. We have analyzed the transition from thin films to a three-dimensional island system at a thickness of 4 ML and the magnetic behavior when increasing the iron coverage to 8 ML. The Fe island system is characterized by a rotation of the easy magnetization axis in this coverage regime.
FARADAY AND MAGNETIC KERR ROTATION MEASUREMENTS ON Co AND Ni FILMS AROUND M2,3 EDGES
Authors: SAITO KATSUHIKO , IGETA MITSUAKI , EJIMA TAKEO , HATANO TADASHI , WATANABE MAKOTO
Published: October 2002

Faraday and longitudinal magnetic Kerr rotation measurements were performed on Co and Ni single layer films around their M2,3 edges, at room temperature under an applied magnetic field of 0.82 T generated by a magnetic circuit composed of permanent magnets. The longitudinal Kerr rotation angle spectra are in good agreement with those calculated from the Faraday rotation spectra in Ni but different in Co. The main reason for the difference in Co was explained with the difference of the magnetization between a longitudinal Kerr (saturated) and a Faraday (unsaturated) configuration under the magnetic field of 0.82 T. This was supported by the calculated result from magnetic circular dichroism (1.2 T, 140 K) measurement on Co.
THEORY OF POLARIZATION DEPENDENCE IN RESONANT X-RAY EMISSION SPECTRA OF A URANIUM COMPOUND
Authors: NAKAZAWA MAKOTO , OGASAWARA HARUHIKO , KOTANI AKIO
Published: October 2002

We calculate the U 5f → 3d5/2 resonant X-ray emission spectra (5f → 3d5/2 RXES) of a uranium compound, UO 3, by means of the Anderson impurity model with full multiplet effects. The calculation is based on the second-order optical formula, and the effect of the X-ray polarization is taken into account. The calculated results of 5f → 3d5/2 RXES show the strong dependence on the X-ray polarization. Using the selection rule of the dipole transition with polarized X-rays, the calculated spectral features are explained.
THE SHAPES OF PHOTOELECTRON SATELLITE SPECTRA
Authors: YARZHEMSKY V. G. , NEFEDOV V. I. , YA. AMUSIA M. , CHERNYSHEVA L. V.
Published: October 2002

Line shapes of photoionization satellites are theoretically investigated. Calculations were carried out for the satellite states 1s2s(3S)3s(2S) and 3s3p5(1P)4s(2P) of Ne 1s and Ar 3p vacancies, respectively, created in photoionization. Theory excellently reproduces experimental line shape parameters of the first satellite and predicts the two-peak structure of the second.
ELECTRONIC CHANGES RELATED TO THE METAL-TO-INSULATOR PHASE TRANSITION IN RNiO3
Authors: PIAMONTEZE CÍNTHIA , TOLENTINO HÉLIO C. N. , VICENTIN FLÁVIO C. , RAMOS ALINE Y. , MASSA NESTOR E. , ALONSO JOSE A. , MARTINEZ-LOPE MARIA J. , CASAIS M. T.
Published: October 2002

Rare earth nickel oxide perovskites (R NiO 3, R=rare earth) have, except for LaNiO 3, a metal–insulator (MI) phase transition as temperature decreases. The transition temperature (T MI ) increases as the R-ion becomes smaller. They present also, at low temperatures, a complex antiferromagnetic order. For lighter R-ions (e.g. Pr and Nd), the antiferromagnetic transition temperature (T N ) is close to T MI , while for heavier R-ions (e.g. Eu, Sm), T MI and T N are very far apart, suggesting that the magnetic and electronic behaviors are not directly coupled. Although R NiO 3 perovskites are placed in the boundary of the Mott–Hubbard and charge transfer regimes, there are several evidences pointing to a charge transfer gap, mainly controlled by ligand-to-metal charge transfer energy, and thus strongly dependent on hybridization. Ni L-edge absorption spectroscopy (transition 2p → 3d) gives direct information on the density of Ni 3d empty states, and in particular on the multiplet splitting and hybridization between Ni 3d and O 2p bands. Here we present Ni L3 and L2 absorption spectra measured for NdNiO 3 and EuNiO 3 (T MI = 200 and 480 K). At room temperature, dramatic differences are observed between EuNiO 3 (insulating) and NdNiO 3 (metallic). The normalized spectra give evidence for a higher density of 3d unoccupied states and a larger multiplet splitting in EuNiO 3. Both effects might be correlated to a decrease in hybridization. The same behavior is observed for NdNiO 3 as it is cooled down to the insulating phase (T < 200 K), revealing that in these compounds the opening of the gap is directly related to the degree of hybridization.
ANISOTROPY OF EXCITON RELAXATION IN BeO CRYSTALS
Authors: YU. IVANOV V. , PUSTOVAROV V. A. , KOROTAEV A. V. , KRUZHALOV A. V. , KIRM M. , ZIMMERER G.
Published: October 2002

This work presents the results of experimental complex study of electronic excitation dynamics for single BeO crystals. The decay kinetics (1–500 ns) of the photoluminescence, reflectivity (8–35 eV), time-resolved emission (2.5–10.4 eV) and luminescence excitation (6–35 eV) spectra were measured at 10 K for the oriented BeO crystals. The diversity among the channels of the radiative relaxation of the electronic excitations as well as the various multiplicity of the excited states of self-trapped excitons, depending on the crystal orientation and exciting photon energy, are discussed.