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1.	Andersen, Jesper N., et al. (författare) Core level binding energy shifts in interfaces between 4d and alkali metals 1995 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 75:C, s. 225-232 Tidskriftsartikel (refereegranskat)abstract High resolution core level photoemission measurements are reported of the binding energy shifts of the 3d core level of Mo, Rh and Pd atoms in interfaces between these 4d metals and alkali metals. The core level binding energies of the interface 4d atoms are found to be almost equal to those of the clean surface atoms for Mo and Rh. For Pd a large alkali induced shift towards higher binding energy is found. The implications of these results for the information derivable from core level binding energy shifts in metallic interfaces are discussed and it is demonstrated that the present results are explained by established total energy based models for core level binding energy shifts in metallic systems.
2.	Bässler, M., et al. (författare) Soft x-ray undulator beam line 1411 at MAX-II for gases, liquids and solid samples 1999 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 101-103, s. 953-957 Tidskriftsartikel (refereegranskat)abstract We report on the build-up of the new undulator beam line 1411 at the third-generation synchrotron radiation facility MAX II in Lund, Sweden. This beam line is based on an upgraded version of the modified SX700-monochromator and the end station which were installed previously at beam line 51 at MAX I. The end station is equipped with a rotatable Scienta hemispherical electron-analyser making angle-resolved high resolution electron spectroscopy possible for various kinds of samples. The beam line performance will be considerably improved on MAX II due to a new undulator and the superior light source properties, e.g. the small vertical electron beam size. Undulator spectra have been measured and estimates of the photon flux at the experiment and the expected energy resolution are presented. The parameters for a new refocusing mirror were defined by ray tracing using the beam waist of the undulator. The beam line length was extended by 1 m to offer additional space for exchangeable experimental chambers.
3.	Denecke, R., et al. (författare) Beamline 1511 at MAX II, capabilities and performance 1999 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 101-103, s. 971-977 Tidskriftsartikel (refereegranskat)abstract The new undulator beamline 1511 at MAX-lab, now under commissioning, has been optimized for X-ray emission and photoelectron spectroscopies. Using an SX-700 high flux monochromator the accessible photon energy range is from 90 eV to about 1500 eV. The performance of the undulator agrees very well with the specifications, as shown by measurements using a photodiode. The energy resolution of the monochromator has been checked using absorption measurements in a gas cell. It was found to meet the expectations and exceeds a resolving power of 10 000 at 244 eV. The photon flux as a function of energy has been recorded as well and gives a maximum flux of 3×1013 photons/s/100 mA/0.1% BW. Beamlines 1511 and 1411 will be the first synchrotron beamlines making use of a so-called beam waist phenomenon, known from laser physics. We show results of ray-tracing calculations to determine the ultimate spot size on the sample location. The endstations to be used at this new beamline and their capabilities will be discussed as an example of the future use of this facility.
4.	Fujikawa, Takashi, et al. (författare) A self-consistent optical potential theory for atoms in solids 1998 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 88-91, s. 649-655 Tidskriftsartikel (refereegranskat)abstract We develop an approximation for the optical potential in a solid, valid at intermediate energies, i.e. energies greater than 50 eV. The present approximation for the optical potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron, and can then achieve a corresponding separation of the optical potential. We apply this method to electron-Ne and -Ar elastic scatterings and find a satisfactory agreement with the observed results. We also study the importance of self-consistency and the sensitivity to a parameter, the average excitation energy.
5.	Hedin, Lars (författare) Optical potentials and damped one-electron functions in photoemission and electron scattering 1990 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 51, s. 91-102 Tidskriftsartikel (refereegranskat)abstract Recently a new approach to photoemission, EXAFS and electron scattering has been developed. The correlations between target electrons are separated from the active electron-target electron correlations, and the damping effects are coming out explicitly. The theory uses van Hove diagonal Green's functions and projection operator techniques, not the usual diagram expansions. By omitting from the start terms in the Hamiltonian which lead to reabsorption of the active electron (photoelectron or scattered electron), remarkably simple expressions are obtained. These expressions contain optical potentials which damp the electron propagation, and “fluctuation potentials” which determine the inelastic scattering. The fluctuation potentials also appear in the expressions for the optical potentials. On the RPA level of approximation the fluctuation potentials are obtained from the dielectric response function of the target. The theory is quite general, but its main advantages are for extended systems, where the damped propagators and damped one electron functions are important effects. The present theory should make it possible to quantitatively attack a number of correlation effects in different spectroscopies.
6.	Hedin, Lars, et al. (författare) Sudden approximation in photoemission and beyond 2002 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 124:2-3, s. 289-315 Tidskriftsartikel (refereegranskat)abstract The conditions behind sudden approximation are critically examined. The fuzzy band expression is derived in detail from first principles. We go beyond the sudden approximation to account for both extrinsic losses and interference effects. In an extension of earlier work we discuss both core and valence satellites including both intrinsic and extrinsic amplitudes, and high energy excitations as well as low energy electron-hole pairs. We show how the extrinsic losses in photoemission can be connected with the electron energy loss function. This is achieved by three approximations, to connect the dynamically screened potential in the bulk solid to the loss function, to account for the surface, and lastly to extrapolate zero momentum loss data to include dispersion. The extrinsic losses are found to be weak for small loss energies. For larger loss energies the extrinsic losses can be strong and have strong interference with the intrinsic losses depending on the nature of the solid. The transition from the adiabatic to the sudden regime is discussed for atoms and localized systems and compared with the situation for solids. We argue that in solids for photoelectron energies above some 10 eV the external losses are mainly connected with spacially extended excitations. We discuss strongly correlated quasi-two-dimensional solids with Bi2212 as example, and find an asymmetric broadening of the main peak from shake up of acoustic three-dimensional plasmons. In the superconducting state the loss function is assumed to have a gap, which then leads to a peak-dip-hump structure in the photoemission spectrum. This structure is compared with a corresponding structure in tunneling. (C) 2002 Elsevier Science B.V. All rights reserved.
7.	Johansson, U., et al. (författare) Thermal desorption of oxides on Si(100) : A case study for the scanning photoelectron microscope at Max-Lab 1997 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 84:1-3, s. 45-52 Tidskriftsartikel (refereegranskat)abstract A scanning photoelectron microscope, utilizing a focused beam of monochromatized photons in the energy range from 15 to 150 eV, has been used to study the thermal desorption of oxide layers on Si(100). The instrument can provide high-resolution photoelectron spectra from selected parts of the surface as well as images showing the lateral distribution (on a micrometer scale) of elements in different chemical states by monitoring the photoemission intensity of chemically shifted core levels. Both native (10-15 Å) and thick (200-400 Å) oxides have been studied. The desorption (at 840°C) of the native oxide proceeds through a phase of irregular (on a micrometer scale) and diminishing areas of dioxide until a clean surface is obtained. For the thick oxide, annealing to 1100°C creates circular voids in the oxide layer which grow linearly in diameter with annealing time. The surface in these voids mainly consists of clean silicon but a small amount of remaining SiO2 is observed. This remaining dioxide most probably consists of small clusters or particles. For both types of oxide, we find, during and after desorption, a surface-shifted component in the Si 2p core level spectra indicating that at least parts of the surface have an ordered structure which most probably is a 2 × 1 reconstruction.
8.	Zakharov, Alexei, et al. (författare) Anisotropy of the electronic structure of low-dimensional Sr(Ca)CuO2 single crystals studied by scanning photoelectron spectromicroscopy 2002 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 122:3, s. 203-208 Tidskriftsartikel (refereegranskat)abstract The energy band structure of superconducting (T-c(onset) = 80 K), low-dimensional Sr(Ca)CuO2 single crystals was studied by photoelectron spectromicroscopy. The sample consists of double parallel Cu-O chains, and spectra show a strong anisotropy for electron momenta k parallel and perpendicular to the chain direction q. Spectra were collected with two experimental setups: kparallel toq (Aperpendicular toq) and kperpendicular toq (Aparallel toq), where A is the electric field vector of the incident photon beam. By imaging the surface on the micrometer scale we find significant variations in the valence band intensity in the vicinity of about 2 eV below the Fermi level for kparallel toq. For this geometry, Aperpendicular toq and the spectra are very sensitive to beam damage. This effect can be related to the breaking of weak inter-chain bonds with the high flux density (similar to10(18) photons s(-1) cm(-2)) beam focused on the sample surface.
9.	Butorin, S. M., et al. (författare) Resonant inelastic soft X-ray scattering at the 4d edge of Ce-based heavy fermion materials 1999 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 101-103, s. 783-786 Tidskriftsartikel (refereegranskat)abstract Resonant X-ray scattering measurements were performed on CeB6, CeAl, γ-Ce, and α-Ce at various incident-photon energies near the Ce 4d threshold. A pronounced inelastic scattering structure which has 4f character is observed at about 4 eV below the elastic peak. The structure shows a distinct resonant behavior as well as a dependence on the degree of 4f hybridization and can therefore be attributed to charge-transfer excitations to the 4f0 state. The intensity of the elastic peak increases when going from the systems with low Kondo temperature TK to those with high TK which is consistent with a Kondo scale behavior. By analyzing the scattering data, a controversial issue on the validity of a single-impurity Anderson model in heavy-fermion materials is addressed.
10.	CHAKAROV, DV, et al. (författare) INTERACTION OF WATER WITH POTASSIUM ON GRAPHITE - A HREELS STUDY 1993 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 64-5, s. 279-285 Tidskriftsartikel (refereegranskat)abstract Water and coadsorbed water + potassium on the basal plane of graphite were studied with high resolution electron energy loss spectroscopy (HREELS) at 85 K and after stepwise annealing up to 500 K. Water adsorbs non-dissociatively on both clean and potassium precovered surface at 85 K. The vibration spectra, together with thermal desorption spectroscopy (TDS) reveal a series of reactions within the coadsorbed layer leading to the formation of KOH, KH, and KOx and volatile products. Eventually a precursor to CO2 formation, of yet unindentified composition and observed also in K + O-2 coadsorption studies on graphite, is observed at approximate to 27 meV.
11.	Crispin, Xavier, et al. (författare) Understanding the initial stages of polymer grafting on metals : A photoelectron spectroscopy study of acrylonitrile adsorption on transition metal surfaces 2001 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 121:1-3, s. 57-74 Tidskriftsartikel (refereegranskat)abstract X-ray and UV photoelectron spectroscopies show that acrylonitrile is chemisorbed on iron, nickel and copper polycrystalline surfaces via the carbon and nitrogen atoms. Depending on the conditions used, different adsorption geometries are found. The molecules can either be adsorbed flat on the surface and chemically bound by a (2pp)-(3d/4s) overlap via both the C=C double bond and the C=N nitrile group or they can be adsorbed perpendicular to the surface via a covalent interaction between the nitrogen lone pair and the 3d-4s levels of the metals. Analysis of the XPS data obtained on molecular mono-layers chemisorbed on metal surfaces emphasizes the importance of initial-state effects (charge transfer upon chemisorption, contribution of the metal surface dipole) and final-state effects (metal screening and polarization effect within the mono-layer). The correlation between the XPS and UPS data illustrates the importance of the metal surface dipole in understanding the workfunction changes upon molecular adsorption on metal surfaces. © 2001 Elsevier Science B.V. All rights reserved.
12.	Giovanelli, L., et al. (författare) Electronic structure of self-assembled organic/inorganic semiconductor interfaces : lead phthalocyanine on InSb and InAs(100)-4X2/c(8 X2) 2001 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 114, s. 375-381 Tidskriftsartikel (refereegranskat)abstract The interfacial properties of ultra thin films of lead-phthalocyanine deposited in situ onto InSb and InAs(100)-4X2/c(8X2) clean surfaces have been studied by synchrotron radiation core level and valence band photoelectron spectroscopy. The interaction between the overlayers and the substrates was determined upon analyzing the changes in the photoemission spectra between room and higher annealing temperatures, leading to ordered monolayer films. While weaker than on other substrates, a reactivity is nevertheless present: the organic macrocycle preserves its integrity up to 320 degreesC but the Pb central atom first leaves the molecules most probably to be incorporated in the substrate surface, before being desorbed at higher temperatures.
13.	Greczynski, G., et al. (författare) Photoelectron spectroscopy of thin films of PEDOT-PSS conjugated polymer blend : A mini-review and some new results 2001 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 121:1-3 Forskningsöversikt (refereegranskat)abstract We present an overview of the photoelectron spectroscopy studies of thin films of the commercially important, electrically conducting polymer blend poly(3,4-ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate), PEDOT-PSS. The issues discussed include the study of thermal effects, the influence of hydrochloric acid on the chemical and electronic structures of the films, phase segregation, as well as the energy level alignment at interfaces employing a PEDOT-PSS layer. All of these issues are important in applications of PEDOT-PSS as a hole-injecting electrode in polymer-based, light-emitting devices. Among the most important results are the identification of the three chemically different species in pristine PEDOT-PSS, namely poly(4-styrenesulfonic acid), poly(sodium 4-styrenesulfonate) and poly(3,4-ethylenedioxythiophene), the conversion of the sodium salt into free poly(styrenesulfonic acid) upon HCl treatment, and the decomposition of the free sulfonic acid component (presumably through loss of SO3H) induced by annealing. It is also shown that phase segregation occurs in the PEDOT-PSS system, resulting in a predominance of PSS in the surface region. This issue has been studied using different approaches, including X-ray photoelectron spectroscopy studies of the sulfur S(2p) and oxygen O(1s) core levels, ultraviolet photoelectron spectroscopy of the valence band region combined with reference measurements and quantum chemical calculations, as well as variable photon energy investigations of sulfur S(2p) core levels. It is demonstrated that, in the context of the energy level alignment at the polymer-metal interfaces, PEDOT-PSS shows metallic-like behavior. Due to the latter, the insertion of a thin PEDOT-PSS layer between the hole-injecting electrode ITO and a polymer layer of poly(bis-(2-dimethyloctylsilyl)-1,4-phenylenevinylene) leads to the lowering of the barrier for hole injection, independent of the work function of the underlying ITO. PEDOT-PSS is also used to show the alignment of the electrochemical potential across metal-polymer-metal structures. © 2001 Elsevier Science B.V. All rights reserved.
14.	Gunnarsson, O., et al. (författare) Information from photoemission spectral weights and shapes 2001 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 117-118, s. 1-11 Tidskriftsartikel (refereegranskat)abstract Photoemission line shapes can be used to extract important information about ground-state and low-energy properties. This is illustrated for the electron–phonon interaction in C60 molecules, the occupancy and hybridization of the 4f-level in Ce compounds, the effect of the Cu–O network on core-level photoemission in cuprates and the properties of one-dimensional conductors.
15.	Hemmers, O., et al. (författare) Dipole and nondipole angular-distribution effects in valence photoemission from neon 2002 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 123:2-3, s. 257-264 Tidskriftsartikel (refereegranskat)abstract Nondipole angular-distribution parameters γ and δ for neon 2s and 2p photoelectrons have been measured and are compared to all available theoretical data. The agreement is very good throughout the 150-1200 eV photon-energy range studied. Furthermore, the neon 2p dipole angular-distribution parameter β and the 2s to 2p cross-section ratio have been measured throughout the same photon-energy range. The agreement between theoretical data and experiment is excellent.
16.	KANSKI, J, et al. (författare) PHOTOEMISSION-STUDIES OF THE GAAS(100)-4X1 SURFACE 1990 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 52, s. 133-138 Tidskriftsartikel (refereegranskat)
17.	Magnuson, Martin, 1965-, et al. (författare) Resonant inelastic soft X-ray scattering spectra at the nitrogen and carbon K-edges of poly(pyridine-2,5-diyl) 1999 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 101-103, s. 573-578 Tidskriftsartikel (refereegranskat)abstract Resonant inelastic scattering measurements of the conjugated polymer, poly(pyridine-2,5-diyl) have been performed at the nitrogen and carbon K-edges using synchrotron radiation. For comparison, molecular orbital calculations of the spectra have been carried out with the repeat unit as a model molecule of the polymer chain. The resonant emission spectra show depletion of the π electron bands which is consistent with symmetry selection and momentum conservation rules. The depletion is most obvious in the resonant inelastic scattering spectra of carbon while the nitrogen spectra are dominated by lone pair n orbital emission of σ symmetry and are less excitation energy dependent. By comparing the measurements to calculations an isomeric dependence of the resonant spectra is found giving preference to two of the four possible isomers in the polymer.
18.	Olovsson, W., et al. (författare) Core level shift in random CuPd and AgPd alloys by the complete screening picture 2002 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 127:02-jan, s. 65-69 Tidskriftsartikel (refereegranskat)
19.	Petoral, Rodrigo Jr, et al. (författare) XPS and NEXAFS study of tyrosine-terminated propanethiol assembled on gold 2003 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 128:2-3, s. 159-164 Tidskriftsartikel (refereegranskat)abstract Tyrosine-terminated propanethiol (TPT), tyrosine linked to 3-mercaptopropionic acid through an amide bond, is adsorbed to gold surfaces. The adsorbates are characterized by means of X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). XPS is used to investigate the chemical binding and electronic structure of the monolayer. Strong molecular binding of the tyrosine derivative on the gold surface through the sulfur atom is attained. Angle-dependent XPS results shows that TPT molecules are oriented with the sulfur atoms molecularly oriented close to the gold surface and that the phenol moiety is oriented away from the gold surface. Average orientation of the adsorbate on gold is deduced using the NEXAFS results. It shows that the main molecular axis is tilted approximately 38° relative to the Au surface normal. The ring plane of the phenol moiety exhibits a preferential orientation with an average tilt angle of the normal of the ring plane from the surface normal of about 60°.
20.	Plashkevych, O., et al. (författare) Calculations of valence electron binding energies using Kohn-Sham theory and transition potentials 2000 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 106:1, s. 51-63 Tidskriftsartikel (refereegranskat)abstract Motivated by the success in computing X-ray photoelectron binding energies and chemical shifts in the core region we apply the Kohn-Sham density functional and transition potential methodology to calculations of binding energies in the valence electron region. Accurate predictions of binding energies over a large energy interval are obtained for a set of molecules for which the quasi-particle approximation holds, but which still have been considered notoriously difficult. The accuracy is found to be a few tenths of an eV in the outermost valence region, slightly poorer in the intermediate region, and seems to be maintained with increasing size of the system.
21.	Privalov, Timofei, et al. (författare) X-Ray absorption and photoionization of laser excited molecules 2003 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 129:1, s. 43-54 Tidskriftsartikel (refereegranskat)abstract This study presents theory and simulations of X-ray absorption and X-ray photoionization spectra of optically excited molecules. The simulations are carried out within a two-step excitation model in which the laser radiation prepares an optically excited state which subsequently is core-electron excited by X-rays. The model makes use of a newly derived time-dependent theory based on the Nozieres-De Dominicis equations. It describes the valence electron relaxation of the optically excited state in the field of the core hole and the implication of this relaxation on the formation of the X-ray spectra. It is found that an optical excitation results in a significant general enhancement of two-electron transitions giving rise to shake-up and shake-down type spectral lines in the X-ray spectra. The excitonic character of the optically excited states is found to considerably influence the formation of the X-ray spectral profile, something that is strongly size- and site-dependent.
22.	QU, H, et al. (författare) VALENCE BANDS AND SURFACE-STATES OF CDTE(110) 1990 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 52, s. 149-154 Tidskriftsartikel (refereegranskat)
23.	Reineck, Ingrid, et al. (författare) Inelastic scattering and satellite fine structure in the high-resolution uv photoelectron spectrum of CS2 1984 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 34:3, s. 235-252 Tidskriftsartikel (refereegranskat)abstract The outer valence region in CS2 has been studied by high-resolution UV photpelectron Spectroscopy. The spectra reveal detailed vibrational structure in the X 2Πg, A 2Πu, B 2Σ+u and C 2Σ+g bands. Some of the fine-structure peaks in the X B and C bands are shown to be pressure-dependent. The reason for the pressure dependence is assumed to be inelastic scattering of electrons emitted in the adiabatic transitions. It is established that the two CI satellite bands present in the He(I)-excited spectrum contain vibrational structure.
24.	Rubensson, Jan-Erik (författare) Soft X-ray emission spectroscopy 1998 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 92:1-3, s. 189-196 Tidskriftsartikel (refereegranskat)abstract New opportunities for soft X-ray emission spectroscopy using monochromatized synchrotron radiation are illustrated with recent results from the Jülich and Uppsala groups. The classical interpretation in terms of local partial density of states is instrumental in gaining information about technically relevant materials, and especially the large photon penetration length is used to study buried structures, interfaces, impurities, and samples under pressure. Information about adsorbates is attained by means of grazing incidence excitation.Momentum conservation in the excitation–emission scattering process is relevant for broad band materials, and gives a k-resolved projection on local angular momentum symmetries. The applicability of this band mapping method is discussed.Energy is relevant for correlated materials with localized excitations a direct consequence is that the line widths in the spectra are limited only by the experimental resolution and the widths of the final states. The life time of the intermediate state does not limit the information content, but can instead be used as an internal time standard for studies of the dynamics.Finally, the connection between lifetime-interference effects and the time evolution of the wavefunctions is discussed.
25.	Rudolf, P, et al. (författare) Studies of fullerenes by the excitation, emission, and scattering of electrons 1999 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 100:1-3, s. 409-433 Tidskriftsartikel (refereegranskat)abstract This paper presents an overview of how electron spectroscopies have contributed to advances in fullerene research. In particular, we illustrate the vital role these techniques have played in improving our understanding of the importance of strong electronic correlation and of electron-phonon coupling in these materials, in the derivation of electron hopping rates, in providing a direct determination of charge transfer and hybridisation in both fullerene salts and adsorbed fullerenes and in determining the optical gap of these systems. We discuss systems of increasing complexity, starting with C60 in the gas phase and in the solid state, and moving on to C60 salts and to C60 adsorbed on surfaces. Finally we look at both higher fullerenes and fullerenes with a heteroatom either on or inside the cage.
26.	Sakamoto, K., et al. (författare) Interaction of metastable molecular oxygen with the dangling bonds of a Si(111)-(7×7) surface 2001 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 114-116, s. 489-494 Tidskriftsartikel (refereegranskat)abstract We have investigated the interaction between metastable molecular oxygen and the adatom dangling bonds modified by the adsorption of atomic oxygen into the back-bonds of a Si(111)-(7×7) surface. Ultraviolet photoelectron spectroscopy shows that the metastable states increase in intensity faster but with a decrease in its saturated intensity as the coverage of atomic oxygen increases. This result suggests that the number of modified dangling bonds is not the only important factor for the adsorption process of metastable oxygen. Taking into account the observation of modified dangling bonds with different density of states in scanning tunneling microscopy, we conclude that the adsorption of the metastable oxygen species correlates closely with the density of states of the dangling bond.
27.	Takata, Y., et al. (författare) Valence excitations observed in resonant soft X-ray emission spectra of K2Ni(CN)4.H2O at the Ni 2p edge 2001 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 114-116, s. 909-913 Tidskriftsartikel (refereegranskat)abstract Resonant soft X-ray emission spectra have been measured at the Ni 2p edge of a planar nickel complex K2Ni(CN)4·H2O and interpreted by performing ab initio configuration interaction calculations. This cyano complex shows characteristic metal-to-ligand charge transfer (MLCT) bands in the Ni 2p photoabsorption spectra. Resonant soft X-ray emission via the MLCT intermediate states can be interpreted as valence MLCT excitations within a one-electron picture. On the other hand, resonant soft X-ray emission via the intra-atomic Ni 2p–3d intermediate state corresponding to the white line excitation shows significant electron correlation effects.
28.	Veenhuizen, Hans, et al. (författare) Acquisition and processing of angle-resolved photoelectron spectra excited with focussed polarized resonance radiation 1986 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 41:2, s. 187-203 Tidskriftsartikel (refereegranskat)abstract A system for the acquisition of angle-resolved photoelectron spectra is described. The sample gas is excited by VUV resonance radiation, which is polarized to about 95% using a fully rotatable fourfold reflection polarizer. One of the mirrors is toroidally shaped in order to focus the radiation into the sample gas cell. This design gives count rates comparable to those obtained by an unpolarized source, and at a greatly reduced background level. A computer controlled system has been developed to automate the recording procedure. It allows for simultaneous recordings of the spectra at the different angular settings, thus eliminating the effects of intensity drifts. Details of calibration procedures and data processing, including spectrum analysis, are given along with a discussion of the accuracy of the results. To illustrate the performance, measured β-values for the main components of the four outermost photoelectron bands in the Hel excited spectrum of CO2 are presented.
29.	Veenhuizen, Hans, et al. (författare) High resolution angle-resolved photoelectron spectrum of CO2, excited with polarized resonance radiation 1986 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 41:2, s. 205-223 Tidskriftsartikel (refereegranskat)abstract The He(I) excited and angle-resolved photoelectron spectrum of CO2 is investigated using a focussing VUV-polarizer. High resolution combined with the additional information given by comparing spectra taken at different angles permits detailed analysis of the vibrational structure. β-values are given for all vibrational components hitherto observed in the photoelectron spectrum of the ≈X, ≈A,≈B and ≈C electronic bands. Single excitations of the v3 mode with vibrational energies 181 meV in the estate and 279 meV in the ≈B-state are reported. The peak at 360 meV vibrational energy in the (≈C-state is reinterpreted as a single v3 excitation. The β-values of the most intense peaks are also measured using Ne(I) (16.67 and 16.85 eV), Ne(II) (26.86 and 26.95 eV) and He(II) (40.81) resonance radiations.
30.	Weiss, K., et al. (författare) XPS and XAS investigation of condensed and adsorbed n-octane on a Cu(110) surface 2003 Ingår i: Journal of electron spectroscopy and related phenomena. - : Elsevier. - 0368-2048. ; 128:2-3, s. 179-191 Tidskriftsartikel (refereegranskat)abstract The electronic structure of n-octane adsorbed on Cu(110) is studied by using X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) in combination with cluster model calculations in the framework of density functional theory (DFT). The molecule is found to be well oriented on the surface, which is seen from the high degree of XAS dichroism. Saturated hydrocarbons are commonly considered to physisorb on metals such as Cu(110), but still the C 1s XAS spectra reveal large changes in the electronic structure of the adsorbed octane relative to the free molecule. We find that the XAS resonances corresponding to the molecular Rydberg-valence states are strongly quenched upon adsorption and that there is a significant hybridization of the molecular valence orbitals with the metal bands. In addition to a precise interpretation of the XAS spectra, we present details on the molecular orbital structure of the adsorbed octane molecule. We also discuss shifts in the relative binding energies of the chemically inequivalent carbon atoms in octane upon adsorption, which lead to a narrower XPS spectrum for the adsorbate than the condensed phase spectrum due to the existence of a new relaxation channel.
31.	Ågren, Hans, et al. (författare) Kramers-Heisenberg and Weisskopf-Wigner descriptions of resonant X-ray Raman scattering 2000 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 110:03-jan, s. 153-178 Tidskriftsartikel (refereegranskat)abstract An overview is presented of the theory of X-ray Raman scattering as originally formulated by Kramers and Heisenberg and by Weisskopf and Wigner. Two particular aspects of the theory are described in some detail; the formation of band profiles and the role of symmetry, These aspects are discussed in connection with recent results for atomic and molecular scatterers obtained in radiative and nonradiative scattering experiments conducted with 2nd and 3rd generation synchrotron radiation sources.
32.	Bustad, Johnny, et al. (författare) Theoretical study of core ionized Cr(CO)6 1995 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 70:3, s. 233-244 Tidskriftsartikel (refereegranskat)abstract The satellite structure of the Cls and Ols photoelectron spectra of chromium hexacarbonyl Cr(CO)(6) has been calculated by the INDO/CI method and compared with available high resolution core level photoelectron spectra. A reassignment of some of the lines is made. It is found that the satellite structure in both cases is dominated by excitations from metal-ligand bonding to metal-ligand antibonding Me(3d)-pi* orbitals, and that these shake-up excitations involve a significant charge transfer to the core ionized ligand from the rest of the molecule.
33.	Wannberg, B., et al. (författare) Imaging properties of electrostatic energy analyzers with toroidal fields 1976 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 9, s. 111-27 Tidskriftsartikel (refereegranskat)abstract Numerical values of the second-order aberration coefficients are given for two classes of toroidal fields, namely (1) the ‘quasi-spherical’ field with c=1, c’≠-1, and (2) fields with c in the region 1.6-1.8. For the ‘quasi-spherical’ fields, the second-order coefficients are given as functions of the deflection angles ω for 90°⩽ω⩽180°. The third-order coefficient for the spherical field are given in the same region. For the devices in the second class, which have one intermediary axial image, the second-order coefficients are studied as functions of c and ω, subject to the conditions that double-focusing should be obtained. The conditions under which the radial and axial image planes coincide are considered. The influence of axially curved entrance and exit surfaces is investigated. One special case (ω=180°, c=1.691, c’=-1.11), which may be favourable for an electron monochromator is discussed
34.	Abukawa, T, et al. (författare) Anomalous diffraction effect on the surface core-level photoemission from Si(001)2x1-Cs surface 1998 Ingår i: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. - : ELSEVIER SCIENCE BV. - 0368-2048. ; 88, s. 539-543 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract The angular dependence of the Si 2p photoelectron intensity has been measured for a Cs-saturated Si(001)2 x 1 surface. A surface Si 2p component, which is attributed to the Si-dimer underneath the Cs overlayer, shows a large intensity variation as a funct
35.	Adak, S., et al. (författare) Study of oxidation states of the transition metals in a series of Prussian blue analogs using x-ray absorption near edge structure (XANES) spectroscopy 2017 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 214, s. 8-19 Tidskriftsartikel (refereegranskat)abstract There have been renewed interests in metal-organic framework classes of materials such as Prussian blue analogues (PBAs) due to their potential usage in energy storage applications. In particular, due to their high surface areas, controllable structures and excellent electrochemical properties, PBAs such as hexacyanometalates MII3[AIII(CN)6]2nH2O (M = Mn, Fe, Co, Ni, Cu, Zn; A = Co, Fe, Cr; n = no. of water molecules present), MII2[FeII(CN)6]2nH2O (M = Mn, Co, Ni, Cu, Zn) and mixed hexacyanometalates(III) (Fe1-xCox)3[BIII(CN)6]2·nH2O (x = 0.25, 0.5, 0.75; B = Co, Fe) could have possible usage as a new class of cathode and even anode materials for rechargeable batteries. Detailed knowledge of the oxidation states of the transition metals in PBAs is required to improve efficiency and durability of such devices. Furthermore, a link between the thermal expansion observed in these materials and the oxidation state of the transition metal is of interest to synthesize materials with a desired thermal expansion behavior, Here we demonstrate the use of Synchrotron based X-ray absorption near-edge structure (XANES) spectra to identify transition metal oxidation states. Our analysis reveals the presence of divalent, trivalent and/or mixed valence transition metals in the materials as well as high-spin and low-spin complexes.
36.	Aksela, S., et al. (författare) Accurate free atom-solid binding energy shifts for Au and Ag 2012 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 185:8-9, s. 273-277 Tidskriftsartikel (refereegranskat)abstract Binding energy shifts between atomic and solid states have been observed with improved accuracy for All 4f and Ag 3d core levels applying a simultaneous measurement method. Also the 3d photoelectron spectrum and binding energies of free Ag atoms have been observed for the first time. New values determined as free atom to bulk solid shifts deviate considerably from previous estimate for Au but agree reasonably well for Ag. The valence bands were also found to shift rather accurately by the same amount as the core levels. (C) 2012 Published by Elsevier B.V.
37.	Alfredsson, Y., et al. (författare) Electronic structure of TiOPc thin film on conducting glass studied by means of X-ray and photoelectron spectroscopies 2009 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 174:1-3, s. 50-54 Tidskriftsartikel (refereegranskat)abstract Thin films of TiOPc have been investigated using photoelectron spectroscopy (PES) and X-ray spectroscopy (XAS). The results are interpreted in terms of the local geometry around the metal center both with regard to bonding and crystal field symmetry. Core and valence PES have been found to be in accordance with the structural characteristics of the TiOPc molecule. For resonant PES at the N1s and Ti2p edges, information on the local electronic structure of the occupied molecular orbitals has been obtained. Ti2p XAS was interpreted in terms of five-fold coordination around the titanium atom for TiOPc of C-4V symmetry. Angle-resolved N1s XAS suggests the molecular planes to order preferentially parallel to the sample surface plane.
38.	Almbladh, Carl-Olof, et al. (författare) Effects of core-level degeneracies on core-level spectra 2004 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 137-40, s. 393-399 Tidskriftsartikel (refereegranskat)abstract Effects of core-level degeneracies on X-ray photoemission spectra are considered theoretically and computationally. Processes within each degenerate sub-level manifold are treated by a leading-order cumulant approximation, and processes which connect spin-orbit or crystal-field split levels to leading order in the core-electron self-energy. The cumulant approximation is consistent with earlier asymptotic results and correctly describe the leading moments of the core-electron spectrum. The central quantity in both cases is an exponent function which may be expressed in terms of projected state densities and core-valence Coulomb matrix elements. Numerical results are presented for the Al L-2.3 and the Rh and Pd M-4.5 levels and compared with recent experiments. In the case of Rh M-4.5, the level-dependent effects are strong leading to an increased asymmetry, a much increased lifetime width of the M-4 level, and deviation from Lorentzian lifetime broadening. In Pd, the effects are much weaker owing to a much smaller Fermi-surface d density of states at the core-hole atom, and it is almost negligible in Al, the most noticeable effect being an increased width of the lower L-2 component. (C) 2004 Elsevier B.V. All rights reserved.
39.	Amati, M., et al. (författare) Scanning photoelectron spectromicroscopy : From static to operando studies of functional materials 2023 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 265 Tidskriftsartikel (refereegranskat)abstract The scanning photoelectron microscope (SPEM), developed more than 30 years ago, has undergone numerous technical developments, providing an incredibly vast kind of feasible sample environments, which span from the traditional high spatial resolution core level based chemical analysis to insitu and operando complex experiments, including also electrochemical setups and operational electronic devices at various temperatures. Another important step ahead is overcoming the so-called pressure gap for operando studies, recently extended to near ambient values by building special environmental cells. Using recent results of conventional and unconventional experiments, obtained with SPEM at the ESCA Microscopy beamline at Elettra Sincrotrone Trieste the present review demonstrates the current potential of this type of photoelectron spectromicroscopy to explore the interfacial properties of functional materials with high spatial resolution.
40.	Andersson, Åke, et al. (författare) Future development plans for the MAX IV light source: Pushing further towards higher brightness and coherence 2018 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 224 Tidskriftsartikel (refereegranskat)abstract The commissioning of the MAX IV synchrotron radiation facility in Lund marks the dawn of a new generation of storage-ring-based light sources. This new generation delivers one order of magnitude higher performance and allows realization of groundbreaking experiments on a variety of systems and materials at the atomic and molecular levels. This paper reviews the conceptual basis of the MAX IV design, briefly summarizes the most recent accelerator commissioning results and focusses on exploring a future development path for the MAX IV 3 GeV storage ring aimed at achieving the diffraction limit at hard x-ray wavelengths.
41.	Antonsson, H, et al. (författare) VIBRATIONAL MOTION AND GEOMETRICAL STRUCTURE IN ADSORBED CO STUDIED BY CORE LEVEL PHOTOELECTRON-SPECTROSCOPY 1990 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 54, s. 601-613 Tidskriftsartikel (refereegranskat)abstract High resolution core level spectra from CO adsorbed on clean and hydrogen precovered Ni(100) and CO adsorbed on Cu(100) are presented. The core level binding energy is shown to be sensitive to the adsorption site. Cluster calculations reproduce the general trend of the binding energy shifts between the on top and hollow sites of CO/Ni(100). In the coadsorption system CO/H/Ni(100) three different adsorption sites have been observed with a maximum binding energy shift of 2.6 eV for the Ols level. The temperature dependence of the Cls and Ols line profiles in CO/Ni(100) has been carefully investigated. The temperature dependent broadening is due to thermal excitations of frustrated translations parallel to the surface. The spectra from CO on Cu(100) show no temperature dependence below 200K.
42.	Arion, Tiberiu, et al. (författare) New insight into the Auger decay process in O-2: The coincidence perspective 2012 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 185:8-9, s. 234-243 Tidskriftsartikel (refereegranskat)abstract Photoelectron-Auger electron coincidence spectroscopy is a powerful tool for the investigation of Auger decay processes with different core-ionized intermediate states. In this paper we describe an investigation into the Auger decay of the O-2 molecule, with the purpose of bringing new insight into the dynamics of the core hole decay mechanism. Using a novel experimental approach to measuring such coincidence spectra we report the highest resolution Auger spectrum of O-2 recorded hitherto. In our approach, we have combined the advantages of these coincidence spectra with the high resolution and excellent signal-to-noise ratios of non-coincident Auger spectra and a state-of-the-art fit analysis. In this way we have derived information about the potential energy curves of the final states W-3 Delta(u), B-3 Pi(g), and B' (3)Sigma(-)(u) and concluded that the corresponding Auger transitions are formed to a large part by strongly overlapping vibrational progressions. The present findings are compared to earlier results reported in the literature confirming some theoretical predictions. (C) 2012 Elsevier B.V. All rights reserved.
43.	Arvanitis, D, et al. (författare) Shape resonances of oriented molecules 2000 Ingår i: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. - : ELSEVIER SCIENCE BV. - 0368-2048. ; 113:1, s. 57-65 Tidskriftsartikel (refereegranskat)abstract We report ab initio calculations of the X-ray absorption cross section for the near edge X-ray absorption fine structure of C2H6, C2H4 and C2H2, at the carbon K-edge, based on a full multiple scattering formalism. We find that shape resonances dominate th
44.	Balasubramanian, Padmanabhan, et al. (författare) Valence band electronic structure of Nd1-xYxMnO3 using X-ray absorption, photoemission and GGA plus U calculations 2013 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 189, s. 51-55 Tidskriftsartikel (refereegranskat)abstract The electronic structures of Nd1-xYxMnO3 (x=0-0.5) were studied using X-ray absorption near-edge structure (XANES) at the Mn L-3,L-2- and O K-edge along with valence-band photoemission spectroscopy (VB-PES). The systematic increase in white-line intensity of the Mn L-3,L-2-edge with doping, suggests a decrease in the occupancy of Mn 3d orbitals. The O K-edge XANES shows a depletion of unoccupied states above the Fermi energy. The changes in the O K-edge spectra due to doping reflects an increase in the Jahn-Teller distortion. The VB-PES shows broadening of the features associated with Mn 3d and O 2p hybridized states and the shift of these features to a slightly higher binding energy in agreement with our GGA + U calculations. The system shows a net shift of the occupied and unoccupied states away from the Fermi energy with doping. The shift in theoretical site-projected density of states of x=0.5 composition with respect to x=0 suggest a subtle change from a charge transfer to Mott-Hubbard type insulator. (C) 2013 Elsevier B.V. All rights reserved.
45.	Bassler, M, et al. (författare) Soft X-ray undulator beam line I411 at MAX-II for gases, liquids and solid samples 1999 Ingår i: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. - : ELSEVIER SCIENCE BV. - 0368-2048. ; 103, s. 953-957 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract We report on the build-up of the new undulator beam line I411 at the third-generation synchrotron radiation facility MAX II in Lund, Sweden. This beam line is based on an upgraded version of the modified SX700-monochromator and the end station which were
46.	Bhatt, Pramod, et al. (författare) Effect of phase formation on valence band photoemission and photoresonance study of Ti/Ni multilayers using synchrotron radiation 2006 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 15:1-2, s. 56-66 Tidskriftsartikel (refereegranskat)abstract This paper presents investigation of Ti–Ni alloy phase formation and its effect on valence band (VB) photoemission and photoresonance study of as-deposited as well as annealed Ti/Ni multilayers (MLs) up to 600 °C using synchrotron radiation. For this purpose [Ti (50 Å)/Ni (50 Å)]X10 ML structures were deposited by using electron-beam evaporation technique under ultra-high vacuum (UHV) conditions. Formation of different phases of Ti–Ni alloy due to annealing treatment has been confirmed by the X-ray diffraction (XRD) technique. The XRD pattern corresponding as-deposited ML sample shows crystalline nature of both Ti and Ni deposited layers, whereas 300 °C annealed ML sample show solid-state reaction (SSR) leading to amorphization and subsequent recrystallisation at higher temperatures of annealing (≥400 °C) with the formation of TiNi, TiNi3 and Ti2Ni alloy phases. The survey scans corresponding to 400, 500 and 600 °C annealed ML sample shows interdiffusion and intermixing of Ni atoms into Ti layers leading to chemical Ti–Ni alloys phase formation at interface. The corresponding recorded VB spectra using synchrotron radiation at 134 eV on as-deposited ML sample with successive sputtering shows alternately photoemission bands due to Ti 3d and Ni 3d, respectively, indicating there is no mixing of the consequent layers and any phase formation at the interface during deposition. However, ML samples annealed at higher temperatures of annealing, particularly at 400, 500 and 600 °C show a clear shift in Ni 3d band and its satellite peak position to higher BE side indicates Ti–Ni alloy phase formation. In addition to this, reduction of satellite peak intensity and Ni 3d density of states (DOS) near Fermi level is also observed due to Ti–Ni phase formation with higher annealing temperatures. The variable photon energy VB measurements on as-deposited and ML samples annealed at 400 °C confirms existence and BE position of observed Ni 3d satellite structure. The observed changes and modifications in the VB photoemission are discussed and interpreted in terms of structural changes at the interface due to annealing treatment.
47.	Bidermane, Ieva, 1984-, et al. (författare) Atomic Contributions to the Valence Band Photoelectron Spectra of Metal-free, Iron and Manganese Phthalocyanines 2015 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 205, s. 92-97 Forskningsöversikt (övrigt vetenskapligt/konstnärligt)abstract The present work reports a photoelectron spectroscopy study of the low-energy region of the valence band of metal-free phthalocyanine (H2Pc) compared with those of iron phthalocyanine (FePc) and manganese phthalocyanine (MnPc). We have analysed in detail the atomic orbital composition of the valence band both experimentally, by making use of the variation in photoionization cross-sections with photon energy, and theoretically, by means of density functional theory. The atomic character of the Highest Occupied Molecular Orbital (HOMO), reflected on the outermost valence band binding energy region, is different for MnPc as compared to the other two molecules. The peaks related to the C 2p contributions, result in the HOMO for H2Pc and FePc and in the HOMO-1 for MnPc as described by the theoretical predictions, in very good agreement with the experimental results. The DFT simulations, discerning the atomic contribution to the density of states, indicate how the central metal atom interacts with the C and N atoms of the molecule, giving rise to different partial and total density of states for these three Pc molecules.
48.	Bournel, F., et al. (författare) 2-Butyne on Si(001) at room temperature: An XPS and NEXAFS study 2011 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 184:3-6, s. 323-326 Tidskriftsartikel (refereegranskat)abstract We present here a study of the adsorption of 2-butyne (CH3-C equivalent to C-CH3) on the Si(0 01)-2 x 1 silicon surface at room temperature using synchrotron radiation photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (NEXAFS). In particular, the Si2p and C1s core levels were followed by real-time photoemission (measuring while dosing). The intensity of the Si2p surface state component gradually diminishes with an increasing exposure to the gas. The C1s photoemission line is decomposed into two main components with their vibrational series, attributed to the two inner carbons (bonded to silicon) and the two methyl carbons (protruding into the vacuum), respectively. C1s real-time XPS indicates that the chemical bonding of the molecule does not change from low coverage to saturation coverage. NEXAFS spectroscopy performed at the C K-edge using linearly polarized radiation reveals the presence of a pi*(C=C) molecular orbital parallel to the surface, resulting from the opening of the triple C equivalent to C bond and the formation of two sigma(Si-C) bonds. The attachment of the molecule via C-H bond scission (conserving the CC bond) is excluded. The clear-cut observation of a C=C bond, combined to our preceding angle-resolved UV photoemission spectroscopy (ARUPS) work [Bournel et al., Surf. Sci. 601 (2007) 3750] favors the on-dimer adsorption model at saturation (similar to 3 L). (C) 2010 Elsevier B.V. All rights reserved.
49.	Boutet, Sebastien, et al. (författare) Ultrafast soft X-ray scattering and reference-enhanced diffractive imaging of weakly scattering nanoparticles 2008 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 166, s. 65-73 Tidskriftsartikel (refereegranskat)abstract We report the first successful reconstruction of the real space image from coherent X-ray diffraction patterns of membrane-supported nanoparticles using single ultrafast pulses. The particles consisted of 145-nm spherical polystyrene spheres that were size-selected by differential mobility analysis. We investigated the dependence of signal intensity on the number of spherical nanoparticles irradiated by single ultrafast pulses at the FLASH FEL facility. We demonstrate detection of as few as two 145-nm diameter particles irradiated by a single 32 nm fs-long FLASH pulse focused to 2.4Jcm(-2). In this case the noise in the diffraction pattern. due to photon-counting statistics and scattering from the supporting silicon nitride membrane, was the largest contributor to the recorded intensity. We were able to reconstruct high-resolution images of the nanoparticles using a strong scattering reference object to aid the phase retrieval of the coherent diffraction pattern. This method of reference-enhanced diffractive imaging may allow the imaging of weakly scattering objects at FLASH and other future X-ray FEL sources.
50.	Burmeister, Florian, et al. (författare) Description and performance of an electron-ion coincidence TOF spectrometer used at the Brazilian synchrotron facility LNLS 2010 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 180:1-3, s. 6-13 Tidskriftsartikel (refereegranskat)abstract This paper reports the characteristics and performance of a Time-of-Flight Mass Spectrometer (TOF-MS) for coincidence measurements between electrons and ions that has been developed jointly in Sweden and Brazil. The spectrometer, used for studies of inner-shell photoexcitation of molecules in the gas-phase, has been optimized by implementing ion and electron lenses to allow the use of relatively small diameter detectors. Simulations were performed to understand the lens performance and they show that ions (electrons) could be collected without angular discrimination with a maximum kinetic energy up to ten (two) times higher than without the lens actions. A rotary vacuum chamber allows the spectrometer axis to be positioned at different angles relative to the polarization vector of the excitation beam. An important characteristic of the apparatus is that the acquisition setup allows a multi-hit capability with 1 ns resolution. Hereby, Photoelectron-Photoion-Photoion Coincidence (PEPIPICO) measurements can be performed on molecules containing two or more atoms of equal mass. A method to obtain experimental detection efficiencies of a single ion and one of one, two or three electrons has been developed. A systematic study of the interaction region has been performed to determine the shape of the photon and gas beams. Measurements on molecular nitrogen demonstrate the spectrometer's ability to resolve fragments with the same charge to mass ratio arriving within only a few ns. Simulations and experimental results of fragmentation of two singly charged cation nitrogen atoms agree, confirming that the spectrometer performance is well understood. (C) 2010 Elsevier B.V. All rights reserved.

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