Search

By employing diverse surface sensitive synchrotron radiation spectroscopies we demonstrate that the fluorine content of initial C

The occupied and unoccupied electronic structures of three high spin TM(acac)

We have investigated the Pt(110) surface by He atom scattering. The (1 x 2) deconstruction transition at 1087 K is shown to fall in 2D Ising universality class with antiphase domain walls proliferating predominantly along the [001] direction. The surface roughening is observed at 1160 ± 10 K through a power law broadening of the anti-phase diffraction peak along the [001] direction. The two distinct phase transition confine the temperature range in which the surface is disordered but still bound to a common height level.

The line shape of the Auger decay of adatoms is studied by a joint theoretical and experimental effort, the former within a DFT framework, and the latter with synchrotron radiation measurements. We investigate the $K{L}_{2,3}V$ Auger deexcitation of Na on Al(111), a system with different adsorption geometries. In particular, we study the $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\text{ }\ifmmode^\circ\else\textdegree\fi{}$ phase at $1/3$ ML (monolayer) and the more complex $(2\ifmmode\times\else\texttimes\fi{}2)$ structure at $1/2$ ML coverage. From the comparison between theory and experiment, we unambiguously determine features that allow for the determination of the adsorption environment from the adatom Auger spectrum.

The resonant photoemission of Cd0.82Mn0.18Te single crystals has been studied in the vicinity of the Mn 2p --> 3d absorption threshold. A clear resonant behavior is detected for valence band states at the Mn 2p --> 3d absorption threshold, while a weak normal Auger emission is singled out in the valence band region for photon energies well above the main absorption edge. Resonant Raman-Auger and normal Auger emissions are found to coexist above the absorption edge. This effect is ascribed to the presence of a manifold of localized states arising from the Mn 2p --> 3d Coulomb and exchange interaction, which prevents the delocalization in the intermediate state of the autoionization process and favors the Raman-Auger process. (C) 2004 Elsevier B.V. All rights reserved.

We present a practical method for the analysis of spectroscopic binaries, reconstructing the lines of the two components of the system. We show that the problem of the separation of binary spectra can be solved in an easy way, under most common conditions. One pair of observations may be sufficient, if taken at different orbital phases of the system, preferably at opposite quadratures. The separation procedure is discussed analytically, and a technique is described, which allows to restore the secondary lines in few steps. An algorithm is also provided, which derives the radial velocity of the secondary star, by directly analysing a difference line-profile obtained from the two input spectra. The efficiency of the method is tested, by reconstructing artificial line-profiles and simulated binary spectra as well. Then the procedure is applied to the eclipsing binary IZ Per , revealing for the first time its faint secondary spectrum.

The gap state that appears upon reduction of TiO2 plays a key role in many of titania's interesting properties but its origin and spatial localization have remained unclear. In the present work, the TiO2(110) surface is reduced in a chemically controlled way by sodium adsorption. By means of resonant photoelectron diffraction, excess electrons are shown to be distributed mainly on subsurface Ti sites strikingly similar to the defective TiO2(110) surface, while any significant contribution from interstitial Ti ions is discarded. In agreement with first principles calculations, these findings demonstrate that the distribution of the band gap charge is an intrinsic property of TiO2(110), independent of the way excess electrons are produced.

We report the detection of 10 new double–line eclipsing binary systems, with first measurements of masses and radii. These results are the preliminary outcome of an observational campaign for detecting new double–line eclipsing systems, carried out at the Observatoire de Haute Provence (OHP) in France, with the 1.52-m telescope and its CCD high–resolution spectrograph Aurelie.

The photoemission spectra of the Sn 4d electrons from the (3×3)-Sn/Ge(111) surface present two components which are attributed to inequivalent Sn atoms in T4 bonding sites. This structure has been explored by photoelectron diffraction experiments performed at the ALOISA beamline of the Elettra storage ring in Trieste (Italy). The modulation of the intensities of the two Sn components, caused by the backscattering of the underneath Ge atoms, has been measured as a function of the emission angle at fixed kinetic energies and vice versa. The bond angle between Sn and its nearest neighbor atoms in the first Ge layer ( Sn–Ge 1) has been measured by taking polar scans along the main symmetry directions and it was found almost equivalent for the two components. The corresponding bond lengths are also quite similar, as obtained by studying the dependence on the photoelectron kinetic energy with the photon polarization and the collection direction parallel to the Sn–Ge 1 bond orientation (bond emission). A clear difference between the two bonding sites is observed when studying the energy dependence at normal emission, where the sensitivity to the Sn height above the Ge atom in the second layer is enhanced. The (3×3)-Sn/Ge(111) is thus characterized by a structure where the Sn atom and its three nearest neighbor Ge atoms form a rather rigid unit that presents a strong vertical distortion with respect to the underneath atom of the second Ge layer.

The temperature-dependent behavior of the Rh(111)-(2X2)-10 phase was investigated by He-atom scattering (HAS) and low-energy electron diffraction. The adsorption system undergoes an order-disorder phase transition at T-c=280+/-5 K, with critical exponents found to be consistent with the four-state Potts model. Beyond the phase transition the HAS specular peak intensity exhibits a strong and reversible increase. This finding points toward a reduction of the surface charge-density corrugation induced by the phase transition itself. Around 160 K, hydrogen adsorbed on the Rh(111)-(2X2)-10 surface reacts with oxygen to form water, and drives the overlayer in an out-of-equilibrium condition which is characterized by a dramatic domain-wall proliferation.

We have investigated the controversy surrounding the (sqrt[3] x sqrt[3]) R30 degrees structure of self-assembled monolayers of methylthiolate on Au(111) by first principles molecular dynamics simulations, energy and angle resolved photoelectron diffraction, and grazing incidence x-ray diffraction. Our simulations find a dynamic equilibrium between bridge site adsorption and a novel structure where 2 CH3S radicals are bound to an Au adatom that has been lifted from the gold substrate. As a result, the interface is characterized by a large atomic roughness with both adatoms and vacancies. This result is confirmed by extensive photoelectron and grazing incidence x-ray diffraction measurements.

The charge distribution of the defect states at the reduced TiO(2)(110) surface is studied via a new method, the resonant photoelectron diffraction. The diffraction pattern from the defect state, excited at the Ti-2p-3d resonance, is analyzed in the forward scattering approach and on the basis of multiple scattering calculations. The defect charge is found to be shared by several surface and subsurface Ti sites with the dominant contribution on a specific subsurface site in agreement with density functional theory calculations.

PHYS. REV. B

We observe that ultrathin Fe/Cu(3)Au(001) films in the 6-13 A thickness range, beyond the thickness of pseudomorphism breakdown at room temperature, exhibit a temperature dependent structural phase transition in the range T(c) approximately 345-380 K. In the high temperature state the Fe film becomes pseudomorphic, while breakdown of pseudomorphism reversibly occurs as the system is cooled below the transition temperature. The difference between substrate and overlayer thermal expansion coefficient is highlighted as the driving force for the observed transition.

Short-range ordering in the form of an excess of In-N bonds with respect to the random case has been recently predicted for the dilute nitride alloy InxGa1-xAs1-yNy. This ordering induces a blue shift of the optical band gap and could represent a fundamental materials limitation. In this report we provide a quantitative determination of the effect of annealing on the short-range ordering in InxGa1-xAs1-yNy, using x-ray- absorption spectroscopy and state-of-the-art analysis methods. We find that in annealed samples short-range ordering is weak, one order of magnitude smaller than predicted.

We present a practical method for the analysis of spectroscopic binaries, reconstructing the lines of the two components of the system. We show that the problem of the separation of binary spectra can be solved in an easy way, under most common conditions. One pair of observations may be sufficient, if taken at different orbital phases of the system, preferably at opposite quadratures. The separation procedure is discussed analytically, and a technique is described, which allows to restore the secondary lines in few steps. An algorithm is also provided, which derives the radial velocity of the secondary star, by directly analysing a difference line-profile obtained from the two input spectra. The efficiency of the method is tested, by reconstructing artificial line-profiles and simulated binary spectra as well. Then the procedure is applied to the eclipsing binary IZ Per, revealing for the first time its faint secondary spectrum.

We present new measurements of He atom inelastic scattering from the (001) surface of Copper. Our results confirmed the recent data obtained in Gottingen and show that at large momentum transfer in the [Formula: see text] direction the intensity of the longitudinal resonance is larger than that of the Rayleigh wave. We interpret these results by evaluating the reflection coefficient in the Distorted Wave Born Approximation. By taking the He surface interaction potential as a sum of nonspherical pairwise potential we are able to explain quantitatively the behavior of the experimental spectra.

not Available.

Note: Univ ljubljana,jozef stefan inst,ljubljana,slovenia. univ trieste,dipartmento fis,i-34127 trieste,italy. Crottini, A, IST NAZL FIS MAT,LAB TASC,PADRICIANO 99,I-34012 TRIESTE,ITALY. ISI Document Delivery No.: XT124 Cited References: BATRA IP, 1986, PHYS REV B, V34, P8246 CIRACI S, 1986, PHYS REV B, V33, P4294 CVETKO D, 1992, MEAS SCI TECHNOL, V3, P997 EDWARDS KA, 1996, PHYSICA B, V221, P201 FEIBELMAN PJ, 1983, PHYS REV B, V27, P1991 FEIBELMAN PJ, 1984, PHYS REV B, V29, P6463 FERRER S, 1995, PHYS REV LETT, V75, P1771 HINCH BJ, 1989, EUROPHYS LETT, V10, P341 HINCH BJ, 1991, VACUUM, V42, P309 HRICOVINI K, 1991, SPRINGER SERIES SURF, V24, P589 JAKLEVIC RC, 1971, PHYS REV LETT, V26, P89 JALOCHOWSKI M, 1992, PHYS REV B, V45, P13607 JALOCHOWSKI M, 1992, PHYS REV B, V46, P4693 LAPUJOULADE J, 1992, SPRINGER SERIES SURF, V27 LENT CS, 1984, SURF SCI, V139, P121 MEYERHEIM HL, 1995, PHYS REV B, V52, P16830 SCHULTE FK, 1976, SURF SCI, V55, P427 TORRELLES X, 1996, SURF SCI, V364, P242 YANG WS, 1995, PHYS REV B, V51, P7571 ZENG H, 1995, PHYS REV LETT, V74, P582 ZHANG Y, 1993, SURF SCI, V293, L821 ZHAO RG, 1993, PHYS REV B, V48, P8462 NR 22 TC 13 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 Reference LOEQ-ARTICLE-1997-016doi:10.1103/PhysRevLett.79.1527 Record created on 2007-08-31, modified on 2017-05-12

The Fe62Ni20Cr18 valence band was studied by scanning the photon energy across the 2p(3/2) core-level threshold of each element of the alloy. A resonant enhancement of the weak 3d-like features was observed. In pure transition metals, similar valence band resonances are explained by a radiation-less Raman de-excitation emission, which is active at threshold and degenerate with the two-hole satellite of direct photoemission. Present structures are associated to satellite features occurring in Fe62Ni20Cr18, and their intensities and binding energies are compared to those of the pure metal components. The alloy satellite resonant behaviour reveals some peculiar modi. cations of: a) the crossover between the radiationless Raman scattering and the Auger emission regimes; b) the ratio of the relative intensities of the main and satellite peaks. We mainly assign these differences to the hetero-nuclear bonds in the alloy.

The electronic properties of a C70 single layer chemisorbed on Cu(1 1 1) surface, in which the charge state has been modified by Na doping, were studied via synchrotron radiation photoemission and absorption spectroscopy. A two-dimensional metallic phase is observed in the whole range of charge states investigated (from 1 up to 3 electrons/C70). Moreover, all the results suggest that the orientation of the molecules, with the C5v axis perpendicular to the surface, is not affected by Na doping.

The C 60 molecules are known to bind covalently to the Pt(1 1 1) surface. We performed a structural study of one C 60 layer on Pt(1 1 1) by using X-ray photoelectron diffraction (XPD). Our results show that the molecules are bonded to the metal surface with their six-carbon rings facing the Pt(1 1 1) surface and with the CC bonds perpendicularly oriented with respect to the direction of the close-packed atom rows. Unlike to what previously found for Cu(1 1 1) and Al(1 1 1), the measured diffraction pattern shows a three-fold symmetry indicating that only one orientation is taken by the chemisorbed molecules. This can be explained by a stronger interaction of the C 60 molecules with the second layer Pt atoms.

The Fe LMM Auger and Auger vacancy satellite spectra of ultrathin Fe films grown on Cu(100) have been measured using photon excitation energies above and below the L 2 ionisation edge, and in coincidence with the Fe 2p 3/2 and Fe 2p 1/2 photoelectrons. A comparison of the relative intensities of the satellites and main Auger transitions indicates that the M 4,5 holes of L 3 M 4,5 double hole states are localised for longer than the L 3 lifetime for the 0.3 and 10 ML coverages but have a lifetime comparable to that of L 3 holes for the 1 ML coverage. The results for the 1 ML coverage are supported by the results of the coincidence experiments. The reasons for the variation in the lifetime of M 4,5 holes are discussed in terms of changes in the number of Fe–Fe neighbours and the density of states at the Fermi energy in these systems.

The atomic-like behavior of the photoionization cross-section of core levels in solids is remarkably displayed in the observation of linear magnetic dichroism in the angular distribution of photoelectrons. Structure-related effects are clearly visible as modulations of the dichroism signal, induced by photoelectron diffraction, a fact that can be exploited to obtain information from magnetic surfaces. A systematic investigation of such effects has been carried out for Fe 2p and 3p core levels on the ALOISA beamline at ELETTRA. We present results for Fe(0 0 1) with a reference calibration for amorphous RCP-Fe grown on Fe30Ni50B20, which provides the atomic-like standard, free from diffraction effects.

The temperature-dependent behavior of the Rh(111)-(2\ifmmode\times\else\texttimes\fi{}2)-1O phase was investigated by He-atom scattering (HAS) and low-energy electron diffraction. The adsorption system undergoes an order-disorder phase transition at ${\mathrm{T}}_{\mathrm{c}}$=280\ifmmode\pm\else\textpm\fi{}5 K, with critical exponents found to be consistent with the four-state Potts model. Beyond the phase transition the HAS specular peak intensity exhibits a strong and reversible increase. This finding points toward a reduction of the surface charge-density corrugation induced by the phase transition itself. Around 160 K, hydrogen adsorbed on the Rh(111)-(2x2)-1O surface reacts with oxygen to form water, and drives the overlayer in an out-of-equilibrium condition which is characterized by a dramatic domain-wall proliferation.

Using He atom scattering, layer-by-layer erosion of InSb(110) by low energy ion bombardment has been observed to proceed via nucleation of vacancy islands, island growth and coalescence. The mechanism is in full agreement with theoretical models developed for crystal growth, with diffusing adatoms substituted by diffusing vacancies. In particular it has been observed that coalescence of the vacancy islands sets in after the removal of small fractions of a monolayer and that the average terrace width increases with increasing number of sputtered monolayers.

Resonant photoemission from the valence band of a (√3 × √3)R30° reconstructed Mn:Ge(111) metallic interface has been carefully analyzed with the aim to track the transition from resonant Raman to normal Auger emission. The transition energy has been compared with the Mn 2p binding energy, as well as with the Mn L(3) absorption edge energy. Close similarities emerge with respect to the case of elemental Mn thin films, suggesting that the excitation dynamics is dominated by the electronic properties of Mn 3d states, in spite of the bonding with Ge atoms. The switching from the resonant Raman Auger (RRAS) to the normal Auger regime is found about 2 eV below the Mn L(3) absorption edge. A change of the lineshape due to the transition from an overall N - 1 electron final state (RRAS channel) to an N - 2 electron final state (normal Auger channel) is evidenced by the analysis of the experimental data, which also allowed the ratio to be tracked between charge delocalization and core-hole time scales as the photon energy is tuned across the Mn L(3) edge.

Charge transfer processes between donor-acceptor complexes and metallic electrodes are at the heart of novel organic optoelectronic devices such as solar cells. Here, a combined approach of surface-sensitive microscopy, synchrotron radiation spectroscopy, and state-of-the-art ab initio calculations is used to demonstrate the delicate balance that exists between intermolecular and molecule-substrate interactions, hybridization, and charge transfer in model donor-acceptor assemblies at metal-organic interfaces. It is shown that charge transfer and chemical properties of interfaces based on single component layers cannot be naively extrapolated to binary donor-acceptor assemblies. In particular, studying the self-assembly of supramolecular nanostructures on Cu(111), composed of iuorinated copperphthalocyanines (F16CuPc) and diindenoperylene (DIP), it is found that, in reference to the associated single component layers, the donor (DIP) decouples electronically from the metal surface, while the acceptor (F16CuPc) suffers strong hybridization with the substrate © 2009 WILEY-VCH Verlag GmbH & Co. KGaA., This work was supported by the European Community through the Integrated Infrastructure Initiative ‘‘European Light Sources Activities – Synchrotrons and Free Electron Lasers’’. The work was further supported through the Spanish Ministerio de Educacio´n y Ciencia (MAT2007-63083, FIS2007-65702-C02-01), ‘‘Grupos Consolidados UPV/EHU del Gobierno Vasco’’ (IT-319-07, IT-257-07), CSIC, and the European Community throughe-I3 ETSF project (Contract Number 211956), and NANO-ERA CHEMISTRY. We acknowledge support by the ‘‘Red Espanola de Supercomputacion’’ and SGIker ARINA(UPV/EHU). J. M. G.-L. acknowledges funding Spanish MEC through Juan de la Cierva program.

The peculiar electrochemical and photophysical properties of porphyrin and fullerene molecules make them promising candidates for the construction of two- and three-dimensional organic-based materials. An important question is how pristine fullerene and porphyrin will organize when deposited on surfaces via in vacuum molecular beam evaporation. Here we show that codeposition of C(70) and Zn-tetraphenyl-porphyrin (ZnTPP) induces the self-assembly of electron-rich flat aromatic molecules at the curved surface of C(70), thus enhancing the chromophore interaction and forming a supramolecular multilayer donor-acceptor structure. While the ground-state electronic spectra almost reflect a simple summation of ZnTPP and C(70) components, the excited-state electrons at the porphyrin macrocycle can rapidly delocalize to the fullerene. The excited charge transfer time scale is faster than 1-2 fs, as shown by resonant photoemission for the core-excited charges.

Resonant photoemission at the Mn 2p --> 3d absorption threshold is used to probe the distribution of the Mn spectral weight in the valence band of Mn thin layers grown onto the CdTe (1 1 0) surface. It is shown that at the early stages of the evaporation process, a Cd-Mn-Te surface alloy is formed, even at room temperature. The Mn 3d spectral weight in the valence band, which is enhanced across the resonance, is quite similar to that observed for Cd1-xMnx Te single crystals. At larger Mn coverages, the growth of a metallic Mn phase on top of the Mn-Cd-Te surface alloy is detected both at resonance and by collecting Mn 2p core level photoemission data. (C) 2004 Elsevier B.V. All rights reserved.

Resonant photoemission spectroscopy data from Cd1-xMnxTe single crystals are presented. A strong resonant behavior, related to the Raman-Auger decay channel arising from the creation of the Mn 2p core hole, is detected for states in the valence-band region at the Mn 2p-->3d absorption threshold. The transition from the resonating Raman-Auger to the weak, normal Auger emission is shown to occur well above the main absorption edge. This effect is ascribed to the presence of a manifold of localized states arising from the Mn 2p-->3d Coulomb and exchange interaction, which prevents the delocalization in the intermediate state of the autoionization process.

The angular distribution of the intensity in photoemission experiments is affected by electron diffraction patterns and by a smoothly varying ISO contribution originated by both intrumental details and physical properties of the samples. The origin of the various contributions to the ISO component has been identified since many years. Nonetheless in this work we present original developement of the ED analysis, which arises from the evolution of instrumental performance, in terms of analyzers positioning and angular resolution, as well as collimation and size of X-ray beams in third generation synchrotron sources. The analytical treatement of the instrumental factors is presented in detail for the end station of the ALOISA beamline (Trieste Synchrotron), where a wide variety of scattering geometries is available for ED experiments. We present here the basic formulae and their application to experimental data taken on the Fe/Cu3Au(001) system in order to highlight the role of the various parameters included in the distribution function. A specific model for the surface illumination has been developed as well as the overlayer thickness and surface roughness have been considered., RevTex, nine pages with five eps figures; to be published in J. Electron Spectrosc. Relat. Phenom

The formation of an alpha-hexathienyl (T6) single layer on the (1 x 2) Au(110) surface has been investigated by means of thermal He atom scattering (THAS) in ultra-high-vacuum (UHV) conditions. The monolayer (ML) structure has a rectangular surface unit cell with the T6 molecules lying flat on the surface and aligned parallel to the Au rows. The periodicity perpendicular to the Au rows is doubled with respect to the bare Au surface, while along the rows it is 27.4 +/- 0.5 Angstrom, corresponding to the molecular length. The correlation length of the overlayer structure depends upon substrate temperature during deposition and increases when the system is heated up to 653 K. The surface structure is irreversibly lost upon heating to temperatures higher than 673 K, but T6 molecules do not completely desorb up to about 773 K.

A helium-atom scattering experiment is reported on the evolution of vacancy islands produced by low-energy ion bombardment on InSb (110). It is seen that island growth occurs through dynamical scaling during the sputtering process, in agreement with the scaling hypothesis that is the basis of nucleation and growth models. After interruption of the sputtering, the spatial distribution of steps on the surface (strictly related to the island size and distance) gradually modifies during the self-organizing surface recovery. In this case the surface reduces its free energy by decreasing the step density; the corresponding increase of the terrace width occurs in the absence of free vacancy supersaturation and the process is diffusion limited. This change of the growth mechanism causes the breaking of dynamical scaling.

The electron density of the (1×2)Pt(110) surface is determined by He reflectivity measurements and compared to the electron densities previously reported for (1×2)Au(110) and (1×2)Rh(110). With respect to the superposition of free atomic electron densities, significant charge depletion and enrichment are observed, respectively, on top of the surface atoms and in the threefold sites of the (111) microfacets.

Coincidence measurements have been extensively performed in atomic and molecular physics since early 1970s. To apply this methodology to solids and surfaces has been a major target since early days, but the long average time needed to complete a coincidence experiment has hampered its attainment. In particular the coincidence technique has not been yet applied in an angle resolved way such for studying the momentum correlation in the ejection of electron pairs from solid surfaces. The experimental chamber at the ALOISA beamline at Elettra. by means of a set of seven homemade electron analyzers, is the first apparatus able to perform Angle Resolved - Auger Photoelectron Coincidence Spectroscopy (AR-APECS) from solid surfaces. In the typical setup ten different pairs of coincident electrons can be measured simultaneously, so reducing the acquisition time by one order of magnitude. (C) 2001 Elsevier Science B.V. All rights reserved.

We show how the anisotropy of the (1 x 2) reconstructed Au(110) surface can be effectively used to achieve spontaneous ordered planar growth of rodlike conjugated oligomers uniaxially oriented on the substrate. The growth of the first few monolayers of alpha-sexithienyl (T6) films on the (1 x 2) reconstructed Au(110) surface in ultrahigh vacuum has been investigated by He atom scattering (HAS), scanning tunneling microscopy (STM), and low-energy electron diffraction (LEED). T6 molecules lie flat on the substrate forming long chains along the [110] direction of the Au rows. The interchain spacing is coverage dependent and uniaxially commensurate with the substrate along [001]. Three ordered structures with 12, 16, and 20 Angstrom periods are formed during the deposition of the first two T6 monolayers. This T6 overlayer acts as a template for the growth of at least five monolayers which are still planar and orientationally ordered.

We report on the Structural and magnetic properties of thin Fe films grown on the Cu(1 1 0) surface. In-plane grazing-incidence X-ray diffraction has been Used to Measure the lateral lattice spacing of the Fe films. Complementary information about the structure of the topmost layers has been obtained by means of Auger and photoelectron diffraction. The Fe film grows pseudomorphic with the substrate up to a thickness of about 0.8 nm. The diffraction feature of a new phase is observed at 1.6 nm, with a corresponding interplanar distance close to the bulk body centered cubic (bee) Fe one, which is eventually recovered at higher thickness (6.4 nm). From comparison between X-ray diffraction and photoelectron diffraction, it is suggested that the bcc-like Fe grows on the (1 0 0) surface with its [1 1 0] axis oriented along the [0 0 1] substrate direction. The photoelectron diffraction data also indicate a strong faceting in the [1 1 0] substrate direction. This morphology is believed to contribute to the in-plane uniaxial magnetic anisotropy observed by Kerr effect and Brillouin light scattering from spin waves.

The feasibility of angle resolved APECS (Auger Photo-Electron Coincidence Spectroscopy) on solids is demonstrated with an experiment performed at the ALOISA (ELETTRA, Trieste) beamline on the L 3 M 45 M 45 Auger transition of the Cu(111) surface. This beam-line, with its multicoincidence detection system based on several individual electron analysers, was designed in order to perform such experiment with good efficiency. The correlation effects displayed by the measured angular distribution are not explained by the two step model, that conversely is commonly accepted for non coincidence experiments performed at the same energy and on the same orbital.

We present a study of low-energy vibrations at the InSb(110) surface along the direction. Surface phonons have been measured by He inelastic scattering and a theoretical analysis has been performed by means of first-principles calculations. We have been able to distinguish the surface acoustic mode above the Rayleigh wave and to identify a surface resonance and an optical surface mode at higher energy. Theoretical calculations are shown to be in agreement with the detected phonon dispersion curves except for the surface resonance which is found 1 meV higher than calculated.