A new LEED instrument for quantitative spot profile analysis

Scheithauer, Uwe; Meyer, Gerd; Henzler, M.

doi:10.1016/0039-6028(86)90321-3

Cited by 287 publications

(57 citation statements)

References 11 publications

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“…This is the case for the SPA-LEED, where the 2D mapping of the reciprocal space is achieved by varying the angle of incidence of the electron beam using electrostatic deflection plates and a channeltron detector with fixed position. 8,18 Furthermore, MCP-LEED and conventional LEED (C-LEED) measurements are typically recorded with a CCD camera equipped with an objective lens system for which a calibration as conducted by Chung et al 11 is not feasible. As the recorded diffraction pattern of a well-known calibration sample without image correction contains the distortions of the entire experimental setup, it can be used to rectify all types of 2D image distortions.…”

Section: Introductionmentioning

confidence: 99%

Determination and correction of distortions and systematic errors in low-energy electron diffraction

Helgert

Meißner

Zwick

et al. 2013

Review of Scientific Instruments

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We developed and implemented an algorithm to determine and correct systematic distortions in low-energy electron diffraction (LEED) images. The procedure is in principle independent of the design of the apparatus (spherical or planar phosphorescent screen vs. channeltron detector) and is therefore applicable to all device variants, known as conventional LEED, micro-channel plate LEED, and spot profile analysis LEED. The essential prerequisite is a calibration image of a sample with a well-known structure and a suitably high number of diffraction spots, e.g., a Si(111)-7×7 reconstructed surface. The algorithm provides a formalism which can be used to rectify all further measurements generated with the same device. In detail, one needs to distinguish between radial and asymmetric distortion. Additionally, it is necessary to know the primary energy of the electrons precisely to derive accurate lattice constants. Often, there will be a deviation between the true kinetic energy and the value set in the LEED control. Here, we introduce a method to determine this energy error more accurately than in previous studies. Following the correction of the systematic errors, a relative accuracy of better than 1% can be achieved for the determination of the lattice parameters of unknown samples.

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Section: Introductionmentioning

confidence: 99%

Determination and correction of distortions and systematic errors in low-energy electron diffraction

Helgert

Meißner

Zwick

et al. 2013

Review of Scientific Instruments

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“…Subsequently the sample was rapidly cooled to liquid nitrogen temperatures. The surface morphology was determined with a spot profile analysis low-energy electron diffraction (SPA-LEED) instrument 26,27 . LEED patterns were taken at a temperature of 80 K and an electron energy of 150 eV.…”

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confidence: 99%

Two-dimensional interaction of spin chains in the Si(553)-Au nanowire system

et al. 2016

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“…In older systems, movable Faraday cup s ( FC s) were used, which were able to detect the electron current directly, but because of the long data acquisition times and problems of transferring motion into ultra -high vacuum ( UHV ) these systems are now rarely used. In fact, only one widely used modern type of LEED optic, which is designed for accurate spot profi le analysis, employs a FC arrangement in combination with a " channeltron " electron detector (the SPA -LEED; see Figure 5.2 ) [8] . In this design, the FC is held in a fi xed position and the grids are replaced by round apertures which defi ne the lateral resolution of the system.…”

Section: Instrumentationmentioning

confidence: 99%

Low‐Energy Electron Diffraction (LEED)

Held

2011

Surface and Thin Film Analysis

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Principles and HistoryWhen Davisson and Germer reported, in 1927, that the elastic scatting of lowenergy electrons from well -ordered surfaces leads to diffraction spots similar to those observed in X -ray diffraction [1 -3] where h is Planck ' s constant, m e the electron mass, v the velocity, and E kin the kinetic energy of the electron. Already, Davisson and Germer realized that the diffraction of low -energy electrons (also termed low -energy electron diffraction ; LEED ) could be used to determine the structure of single crystal surfaces, in analogy to X -ray diffraction, if their kinetic energy was between 40 and 500 eV -that is, if their wavelength ranged between 0.5 and 2 Å . Due to their small inelastic mean free path ( IMFP ) of only a few Å ngstroms (typically < 10 Å ), electrons in this energy range sample only the topmost atomic layers of a surface and are, therefore, better suited for the analysis of surface geometries than X -ray photons, which have a much larger mean free path (typically of a few micrometers). However, unlike for photon diffraction, multiple scattering plays an important role in the diffraction process of electrons at solid surfaces. Therefore, the analysis of LEED data with respect to the exact positions of atoms at the surface is somewhat more complicated, and requires fully dynamical quantum mechanical scattering calculations. The use of LEED for surface analysis became important when suffi ciently large single crystals became available for surface studies. Initially, the technique was used only for the qualitative characterization of surface ordering and quantitative determination of the two -dimensional ( 2 -D ) surface lattice parameters (e.g., superstructures, see below). Information regarding the positions of the atoms in the

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A new LEED instrument for quantitative spot profile analysis

Cited by 287 publications

References 11 publications

Determination and correction of distortions and systematic errors in low-energy electron diffraction

Determination and correction of distortions and systematic errors in low-energy electron diffraction

Two-dimensional interaction of spin chains in the Si(553)-Au nanowire system

Low‐Energy Electron Diffraction (LEED)

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