X-RAY PHOTOELECTRON DIFFRACTION STUDY OF A LONG-RANGE-ORDERED ACETATE LAYER ON Ni(110)

2000 ◽  
Vol 07 (01n02) ◽  
pp. 25-36 ◽  
Author(s):  
M. NOWICKI ◽  
A. EMUNDTS ◽  
J. WERNER ◽  
G. PIRUG ◽  
H. P. BONZEL
Keyword(s):  
Room Temperature ◽  
Solid Angle ◽  
Single Scattering ◽  
Real Space ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Acetate Complex ◽  
Cluster Calculations ◽  
Model Layer ◽  
Good Agreement

An investigation of acetic acid adsorption on Ni(110) at room temperature by LEED and X-ray photoelectron diffraction reveals a well-ordered c(2 × 2) acetate overlayer with a molecular coverage near 0.5. Large solid angle maps of angle-resolved C 1s and O 1s intensities from this layer show intense maxima due to electron forward scattering by nearby atoms, either of the same acetate or of neighboring acetate species. The data provide strong evidence for acetate in a bidentate configuration, bonded through both oxygen atoms to the surface and aligned along the [Formula: see text] surface azimuth. A real space model for the c(2 × 2) acetate layer has been derived and single scattering cluster calculations for this model layer have been carried out for C 1s and O 1s emissions. Allowing for changes in intramolecular bond length of the acetate relative to those in a Ni-acetate complex, good agreement between experimental and theoretical C 1s and O 1s distributions was obtained.

STRUCTURAL DETERMINATION OF THE Si/Cu(110) INTERFACE BY PHOTOELECTRON DIFFRACTION

1997 ◽  
Vol 04 (06) ◽  
pp. 1331-1335 ◽  
Author(s):  
C. ROJAS ◽  
J. A. MARTÍn-GAGO ◽  
E. ROMÁN ◽  
G. PAOLUCCI ◽  
B. BRENA ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Parameters ◽  
Single Scattering ◽  
Structural Determination ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
First Order ◽  
Proposed Model ◽  
Laboratory Source

Deposition of 0.5 Si monolayer (ML) on a Cu (110) surface at room temperature (RT) leads to the formation of a c(2×2) LEED pattern. In order to find out the surface atomic structure of this ordered phase, X-ray photoelectron diffraction (XPD) azimuthal scans at different photon energies and full hemispherical XPD patterns of the Si 2 p core level have been measured using both synchrotron radiation and a laboratory source. We present an atomic model for the surface structure based on the examination of forward scattering and first order interference XPD features. Refinement of the structural parameters was achieved by performing single scattering cluster (SSC) calculations. In the proposed model Si atoms replace Cu atoms at the surface along the [Formula: see text] atomic rows.

Structure determination of the 1/1 α/β mixed lactose by X-ray powder diffraction

2005 ◽  
Vol 61 (4) ◽  
pp. 455-463 ◽  
Author(s):  
Jacques Lefebvre ◽  
Jean-François Willart ◽  
Vincent Caron ◽  
Ronan Lefort ◽  
Frédéric Affouard ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Size Effects ◽  
Room Temperature ◽  
Real Space ◽  
Hydroxyl Groups ◽  
Soft Constraints ◽  
Rietveld Refinements ◽  
X Ray ◽  
Mixed Compound

The mixed form of α/β lactose was obtained by heating amorphous α-lactose at 443 K. NMR spectroscopy determined the stoichiometry of this mixed compound to be 1/1. The X-ray powder diffraction pattern was recorded at room temperature with a sensitive curved detector (CPS 120). The structure was solved by real-space methods (simulated annealing) followed by Rietveld refinements with soft constraints on bond lengths and bond angles. The H atoms of the hydroxyl groups were localized by minimization of the crystalline energy. The cell of 1/1 α/β lactose is triclinic with the space group P1 and contains two molecules (one molecule of each anomer). The crystalline cohesion is achieved by networks of O—H...O hydrogen bonds. The width of the Bragg peaks is interpreted through a microstructural approach in terms of isotropic strain effects and anisotropic size effects.

scholarly journals Compositional Dependence of Structural Properties of Prepared Alloys and Films

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
M. F. A. Alias ◽  
A. A. J. Al-Douri ◽  
E. M. N. Al-Fawadi ◽  
A. A. Alnajjar
Keyword(s):  
Room Temperature ◽  
Thermal Evaporation ◽  
High Accuracy ◽  
Compositional Dependence ◽  
X Ray Diffraction ◽  
Thermal Evaporation Method ◽  
X Ray ◽  
Glass Substrates ◽  
Different Temperatures ◽  
Good Agreement

Results of a study of alloys and films with various Pb content have been reported and discussed. Films of of thickness 1.5 μm have been deposited on glass substrates by flash thermal evaporation method at room temperature, under vacuum at constant deposition rate. These films were annealed under vacuum around 10−6Torr at different temperatures up to 523 K. The composition of the elements in alloys was determined by standard surfaces techniques such as atomic absorption spectroscopy (AAS) and X-ray fluorescence (XRF), and the results were found of high accuracy and in very good agreement with the theoretical values. The structure for alloys and films is determined by using X-ray diffraction. This measurement reveals that the structure is polycrystalline with cubic structure and there are strong peaks at the direction (200) and (111). The effect of heat treatment on the crystalline orientation, relative intensity, and grain size of films is presented.

Growth of Fe on Ge(111) at room temperature studied by X-ray photoelectron diffraction

2007 ◽  
Vol 601 (3) ◽  
pp. 638-648 ◽  
Author(s):  
W.G. Chu ◽  
A. Tsuruta ◽  
M. Owari ◽  
Y. Nihei
Keyword(s):  
Room Temperature ◽  
X Ray ◽  
Photoelectron Diffraction

scholarly journals Surface science at the PEARL beamline of the Swiss Light Source

2017 ◽  
Vol 24 (1) ◽  
pp. 354-366 ◽  
Author(s):  
Matthias Muntwiler ◽  
Jun Zhang ◽  
Roland Stania ◽  
Fumihiko Matsui ◽  
Peter Oberta ◽  
...  
Keyword(s):  
Light Source ◽  
Surface Science ◽  
Photoelectron Spectroscopy ◽  
Hexagonal Boron Nitride ◽  
Real Space ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Swiss Light Source

The Photo-Emission and Atomic Resolution Laboratory (PEARL) is a new soft X-ray beamline and surface science laboratory at the Swiss Light Source. PEARL is dedicated to the structural characterization of local bonding geometry at surfaces and interfaces of novel materials, in particular of molecular adsorbates, nanostructured surfaces, and surfaces of complex materials. The main experimental techniques are soft X-ray photoelectron spectroscopy, photoelectron diffraction, and scanning tunneling microscopy (STM). Photoelectron diffraction in angle-scanned mode measures bonding angles of atoms near the emitter atom, and thus allows the orientation of small molecules on a substrate to be determined. In energy scanned mode it measures the distance between the emitter and neighboring atoms; for example, between adsorbate and substrate. STM provides complementary, real-space information, and is particularly useful for comparing the sample quality with reference measurements. In this article, the key features and measured performance data of the beamline and the experimental station are presented. As scientific examples, the adsorbate–substrate distance in hexagonal boron nitride on Ni(111), surface quantum well states in a metal-organic network of dicyano-anthracene on Cu(111), and circular dichroism in the photoelectron diffraction of Cu(111) are discussed.

THE SURFACE STRUCTURE OF A LOW Pd Cu/Pd-(110) CRYSTAL ALLOY

1994 ◽  
Vol 01 (04) ◽  
pp. 569-571 ◽  
Author(s):  
M. BOWKER ◽  
M. NEWTON ◽  
S.M. FRANCIS ◽  
M. GLEESON ◽  
C. BARNES
Keyword(s):  
Surface Structure ◽  
Surface Region ◽  
Single Scattering ◽  
Alloy Surface ◽  
High Concentration ◽  
Near Surface ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Layer 2

X-ray photoelectron diffraction studies of this alloy surface have been carried out and indicate that there is a significant expansion of the lattice in the near-surface region due to the high concentration of Pd in layer 2. Preliminary single scattering calculations lend support to this proposal for the surface structure, and place this expansion in the subsurface mainly between layers 2 and 3.

Vapour growth, morphology, absolute structure and pyroelectric coefficient of meta-nitroaniline single crystals

2019 ◽  
Vol 52 (3) ◽  
pp. 564-570 ◽  
Author(s):  
Rolf Hesterberg ◽  
Michel Bonin ◽  
Martin Sommer ◽  
Matthias Burgener ◽  
Bernhard Trusch ◽  
...  
Keyword(s):  
Room Temperature ◽  
Vapour Phase ◽  
Pyroelectric Coefficient ◽  
Growth Speed ◽  
Published Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Absolute Structure ◽  
Good Agreement

The growth speed of (hkl) faces in the vapour phase, the absolute structure obtained by X-ray crystallography, and the value and the sign of the pyroelectric coefficient of meta-nitroaniline (mNA) were analysed in detail. The in situ observation of morphologically well developed faces of several mNA crystals growing in evacuated ampoules reveals no pronounced growth speed anisotropy for polar faces defining the unique axis 2 of the mm2 group. Scanning pyroelectric microscopy confirms mono-domain mNA crystals. X-ray measurements in the space group Pca21 show that the molecular planes coincide with the {\bar 211} and {\bar 2\bar 1\bar 1} faces, and the nitro groups cover the {201} face in the opposite direction to the crystal tip, characterizing the polar habitus studied here. At room temperature, the sign of the pyroelectric coefficient is positive for a measured effective value of 6.3 µC m−2 K−1, in good agreement with values reported by other authors. From previous elastic and piezoelectric published data, the secondary pyroelectric effect was calculated to be positive and far greater than the effective one, yielding a negative value for the primary pyroelectric coefficient.

Sign in / Sign up

Export Citation Format

Share Document