Showing papers by "Fritz Haber Institute of the Max Planck Society published in 1985"
TL;DR: It is concluded that only a self-consistent theory like the TDLDA (or an improvement of it) is able to account for all the complexity of the electronic response in small dimensions.
Abstract: The dynamical electronic response properties of small metal particles are calculated within the frame of the self-consistent spherical jellium model. The method used is the TDLDA (time-dependent local-density approximation) with the inclusion of exchange and correlation. In this way we obtain for the first time insight into the nonlocal electronic response properties at a strictly microscopic level. The size dependence of photoabsorption, photoemission, and of the static polarizability, is discussed in detail. The emergence of the collective volume mode (the volume plasmon) as a function of the numbers of electrons is shown here for the first time. Likewise, the size-dependent Landau damping of these modes is obtained in a quantitative fashion. Compared with the results of any non-self-consistent model, we conclude that only a self-consistent theory like the TDLDA (or an improvement of it) is able to account for all the complexity of the electronic response in small dimensions.
354 citations
TL;DR: The adsorption of CO at 85 K on the Pt-s[4(111)×(100)] surface has been investigated using infrared reflection-absorption spectroscopy (IRAS) TPD and LEED as mentioned in this paper.
255 citations
TL;DR: In this paper, the spraying method was used to prepare amorphous and partially crystalline tin dioxides at temperatures from 340 to 410°C and polycrystalline tin compounds at temperatures between 420 to 500°C, respectively.
175 citations
TL;DR: In this paper, the electrochemical and optical properties of reconstructed Au(100)-(5×20) electrodes were investigated in aqueous electrolytes and the potential zero charge and overall electroreflectance effect were found to be similar to Au(111).
124 citations
TL;DR: In this article, the same overlayer of CO at 7 K exhibits only one of the two bridging CO bands as well as the linear bands at frequencies associated with bridging species (ν(CO) = 1830 and 1812 cm − ).
119 citations
TL;DR: Determination de l'orientation et des sites d'adsorption du formiate sur la surface de cuivre sur the surface ofCuivre(110)
Abstract: A unique assignment of both the orientation and the adsorption site of formate (HCOO) on Cu(110) has been made by analysis of near-edge and extended x-ray-absorption fine structure. The species lies with its molecular plane perpendicular to the surface, aligned along the [$1\overline{1}0$] directions, and on top of the copper atoms of the outermost layer; the oxygen atoms almost bridge two copper atoms with an average Cu-O bond length of 1.98\ifmmode\pm\else\textpm\fi{}0.07 \AA{}, essentially identical to that in bulk copper formate.
106 citations
TL;DR: In this article, the infrared spectrum was used to study the vibration of CO adsorbed on small, silica-supported platinum particles, and three bands can be detected on each of the different samples.
99 citations
01 Sep 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a toroidal grating monochromator designed for operation in the soft X-ray region at the synchrotron radiation source BESSY is described.
Abstract: A toroidal grating monochromator designed for operation in the soft X-ray region at the synchrotron radiation source BESSY is described. With three in situ interchangeable gratings the instrument covers the spectral range 180 to 1150 eV. The current (source size-limited) resolution is 0.39, 0.7 and 2.6 eV at photon energies of 250, 400 and 800 eV, respectively. The photon flux is typically 8 × 10 11 photons s −1 (100 mA ) −1 (Δ h ω) −1 . Photoemission experiments on free molecules and on solid surfaces have been used to demonstrate the performance of the monochromator.
98 citations
TL;DR: In this paper, the full orientation dependence of oxygen adsorption at temperatures between 350 and 870 K was investigated on a cylindrical Si sample using Auger electron spectroscopy and synchrotron radiation excited valence band and core level photoemission.
86 citations
TL;DR: In this paper, the physical properties of amorphous solid water are discussed with respect to embedding of organic specimens and conditions and pitfalls associated with preparation of thin and entirely vitrified ice layers by shock-freezing are described.
55 citations
TL;DR: Results are in contrast to earlier predictions that such extremely beam-sensitive materials could not be studied directly at this level of detail, giving direct evidence for crystal bending as well as direct visualization of edge dislocations in this material.
Abstract: A liquid helium-cooled cryoelectron microscope, operated to expose the specimen to only a very low electron dose, was used to obtain structural images of monolamellar n-tetratetracontane (n-C44H90) crystals at 0.25-nanometer resolution. These results are in contrast to earlier predictions that such extremely beam-sensitive materials could not be studied directly at this level of detail. Analysis of the resultant lattice images gives direct evidence for crystal bending as well as direct visualization of edge dislocations in this material.
TL;DR: In this article, angle-resolved UV photoelectron spectra were measured for the ZnO(10 1 0) surface using synchrotron radiation in the energy range from 20 to 80 eV.
TL;DR: The photoelectrons ejected by vacuum ultraviolet radiation in a region of a very weak field from the lone-pair orbital located at the iodine atom show a pronounced asymmetry depending on whether electrons are emitted parallel or antiparallel to the molecular axis.
Abstract: A photoionization experiment on free oriented molecules in the gas phase has been performed. ${\mathrm{CH}}_{3}$I molecules in a supersonic beam have been oriented with respect to the molecular axis parallel to an external field by use of an electric hexapole. The photoelectrons ejected by vacuum ultraviolet radiation in a region of a very weak field from the lone-pair orbital located at the iodine atom show a pronounced asymmetry depending on whether electrons are emitted parallel or antiparallel to the molecular axis.
TL;DR: In this article, a cylindrically shaped Si crystal was used to investigate the interaction of H2O with the main orientations (001), (111), and (110) between 100 and 900 K by photoelectron spectroscopy.
TL;DR: Evidence is presented from cluster calculations that the splitting is caused by the occurrence of two classes of negative-ion final states, which are bonding with respect to Cu and CO and in the second class in an orbital which is antibonding.
Abstract: The inverse photoemission spectrum of CO adsorbed on the CU(100) surface reveals a split CO 2\ensuremath{\pi}--derived feature. For the ordered overlayers at high coverage, band dispersion of both components is clearly observed. We present evidence from cluster calculations that the splitting is caused by the occurrence of two classes of negative-ion final states. In the first (lower-energy) class, the added electron is in an orbital which is bonding with respect to Cu and CO and in the second class in an orbital which is antibonding.
TL;DR: By use of circularly polarized synchrotron radiation at BESSY, spin-polarized photoemission from the valence orbitals of Xe and Kr atoms adsorbed on the Pt(111) single-crystal surface has been studied.
Abstract: By use of circularly polarized synchrotron radiation at BESSY, spin-polarized photoemission from the valence orbitals of Xe and Kr atoms adsorbed on the Pt(111) single-crystal surface has been studied. Under certain conditions almost complete photoelectron polarization parallel or antiparallel to the photon spin was observed, allowing a direct assignment of quantum numbers of the states involved. Highly resolved intensity and polarization spectra in the threshold region exhibit pronounced variations versus photon energy.
TL;DR: Investigation of the orientation dependence of the photoionization threshold and the surface position of the valence-band edge below the Fermi level on a cylindrically shaped Si crystal found that increasing corrugation on stepped, faceted, defect-rich, and high-index surfaces increases £xi values, in contrast to what is observed on metal surfaces.
Abstract: Photoelectron spectroscopy, including emission from the Si 2p core level, was used to investigate the orientation dependence of the photoionization threshold \ensuremath{\xi}(\ensuremath{\alpha}) and the surface position of the valence-band edge below the Fermi level, ${E}_{\mathrm{VFS}}$(\ensuremath{\alpha}), on a cylindrically shaped Si crystal with [11\ifmmode\bar\else\textasciimacron\fi{}0] as its axis. The average \ensuremath{\xi} values for (001), (113), (111), and (110) are 5.33, 5.32, 5.26, and 5.26 eV, respectively, and thus differ only very little as expected for a covalent, nonpolar crystal. Increasing corrugation on stepped, faceted, defect-rich, and high-index surfaces increases \ensuremath{\xi} values, in contrast to what is observed on metal surfaces. The orientation dependence of \ensuremath{\xi} is interpreted in terms of a relaxation- or reconstruction-related surface polarity which is increased at edges. Water adsorption generally reduces \ensuremath{\xi}. In the range (001)--(113) the shape of \ensuremath{\xi}(\ensuremath{\alpha}) is conserved, whereas it is changed in the range (112)--(111)--(110), consistent with fundamentally different adsorption mechanisms as observed earlier. After oxygen adsorption, \ensuremath{\xi}(\ensuremath{\alpha}) is strongly changed, indicating a strong distortion of the surface by bond breaking. On the clean surface, the Fermi-level--pinning position ${E}_{\mathrm{VFS}}$(\ensuremath{\alpha}), which is given by the surface-state structure, varies strongly. After oxygen exposure it is pinned at a nearly constant position \ensuremath{\sim}0.1 eV above the midgap, probably by defect-related surface states. For water adsorption, again two ranges can be distinguished with a similar pinning as for oxygen in the range (112)--(111)--(110) and a reduced but still strong variation between (001) and (113).
TL;DR: In this article, it is shown that there are definite values of hollow-cone angle and defocus for imaging heavy-atom structures on an amorphous carbon film with minimum disturbing noise.
15 Sep 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The characteristics of synchrotron radiation in the infrared region have been investigated at the Berlin electron storage ring BESSY using Fourier spectroscopy as discussed by the authors, and it was found that BESSy at 100 mA beam current delivers higher fluxes than a conventional source only in the spectral region below 30 cm−1, provided the interferometer is the throughput-limiting element.
Abstract: The characteristics of synchrotron radiation in the infrared region have been investigated at the Berlin electron storage ring BESSY using Fourier spectroscopy. In accordance with calculation, it was found that BESSY at 100 mA beam current delivers higher fluxes than a conventional source only in the spectral region below 30 cm−1, provided the interferometer is the throughput-limiting element. If, however, the throughput is limited by small sample size or, if the experiment requires a large f-number, the high brightness of synchrotron radiation could already yield flux advantages at several hundred wavenumbers. The possible application in one particular experiment - infrared reflection-absorption spectroscopy of adsorbed molecules on metal single crystal surfaces - is discussed. In the course of the investigations described here, it was also established that the short light pulses of the synchrotron radiation (∼ 100 ps) do not adversely affect the resolution in Fourier transform spectroscopy.
TL;DR: In this article, the reactivities of interfaces formed by deposition of metals onto the basal face of molybdenum disulphide were investigated by soft X-ray photo-emission spectroscopy using synchrotron radiation.
TL;DR: The use of extended X-ray absorption fine structure (EXAFS) to determine the interatomic distances in small metal clusters is of considerable scientific as well as technical importance as mentioned in this paper.
TL;DR: In this article, a tight-binding cluster calculation including interatomic Coulomb repulsion for field-induced adsorption and desorption was presented, and the variation of the Schottky barrier and of the N 2 vibrational frequency was extracted as a function of F.
TL;DR: The bulk and surface valence v-bar of Yb is investigated for YbPd/sub x/ intermetallic compounds by photoemission using synchrotron radiation and the results are compared with bremsstrahlung isochromat spectroscopy measurements and predictions based on Miedema's scheme.
Abstract: The bulk and surface valence v\ifmmode\bar\else\textasciimacron\fi{} of Yb is investigated for ${\mathrm{YbPd}}_{\mathrm{x}}$ intermetallic compounds (with x=1,1.33,3) by photoemission using synchrotron radiation. YbPd is found to be of intermediate valence (v\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\simeq}2.75), while ${\mathrm{Yb}}_{3}$${\mathrm{Pd}}_{4}$ and ${\mathrm{YbPd}}_{3}$ are identified as bulk trivalent systems. The outermost atomic surface layer of both YbPd and ${\mathrm{Yb}}_{3}$${\mathrm{Pd}}_{4}$ is found to be divalent, while only a fraction of Yb surface atoms turns divalent in ${\mathrm{YbPd}}_{3}$. The results are compared with bremsstrahlung isochromat spectroscopy measurements and predictions based on Miedema's scheme.
TL;DR: Raman and fluorescence spectra are measured for germanium molecules in this article, and the Raman band at 274 cm−1 can be attributed to Ge2, while the other Raman bands are assigned to the linear trimer and tetrahydral quadromer.
TL;DR: In this article, the spatial origin of electroluminescence (EL) and photoluminecence (PL) spectra in the n-GaP/redox electrolyte system were measured at different excitation levels.
TL;DR: In this paper, a theory has been developed which accounts for certain deviations from the ideal cyclic voltammetric behavior of molecules adsorbed irreversibly on electrode surfaces.
TL;DR: In this paper, layer-dependent shifts of core-level binding energies and Auger electron kinetic energies are reported for epitaxial multilayers for Xe, Kr, and Ar adsorbed on graphite (001).
TL;DR: A theoretical discrepancy concerning band crossings at two points along the Lambda direction in Pt is clarified by experimental symmetry analysis of the band characteristics, using circularly polarized synchrotron radiation and spin analysis ofThe photoelectrons by a new low-energy-diffraction analyzer system.
Abstract: A theoretical discrepancy concerning band crossings at two points along the \ensuremath{\Lambda} direction in Pt is clarified by experimental symmetry analysis of the band characteristics, using circularly polarized synchrotron radiation and spin analysis of the photoelectrons by a new low-energy-diffraction analyzer system. Each of the theoretical results is found to be correct at one k point and incorrect at the other one.
TL;DR: In this paper, thin anodic oxide films were allowed to grow on the surface of n-type GaAs electrodes and the dissolution rate of these films was controlled by the rotating electrode technique.
TL;DR: In this paper, the title compound was shown by both X-ray analysis and MNDO calculations to prefer a doubly lithium bridged cis structure (C 2 rather than C 2v ) in contrast to the trans geometry expected for the isolated 1,4-diphenylbutadiene dianion.