1,721,808 research outputs found
Evolution of optical response in the series YbCu5-xAux
No full textOptical measurements from the far infrared to ultraviolet and at low temperature are used to study the evolution of Kondo lattice behaviors within the series YbCu5-xAux. Heavy fermion (Kondo lattice) features have been observed in the low energy part of the spectrum of YbCu5, resembling the data of the isostructural YbCu4Ag, but for a shift towards the lowest frequencies of the free carrier behavior (consistent with a lower TK value). By moving to samples with an increasing amount of Au atoms substituting the Cu atoms, three effects can be observed: the closing of the hybridization gap signed by the red shift of a typical structure in the optical conductivity; the increasing amount of broadening effects, possibly related to stoichiometric disorder; the disappearing of a vibrational structure at about 3.5 meV, which could be due or to disordering effects, or to a change in the Yb–Cu (Yb–Au) bonds
The origin of extra spots in low electron diffraction
No full textMany low energy electron diffraction (LEED) patterns contain extra spots which can be caused by a large number of different atomic arrangements. LEED can, at present, give only information on the lateral periodicity of the atomic arrangement but does not allow determination of the positions of the atoms within the lateral periodicity unit and normal to the surface. Such information has to be obtained from other experiments, of which Auger electron spectroscopy and work function measurements are particularily useful. The present status of the understanding of the origin of extra spots as obtained from such measurements is illustrated by two examples : a simple pattern with extra spots, the W (110)-p (2 x 1) — 0 pattern, and a complex pattern with extra spots, the Si (111) — 7 x 7 pattern.L'origine des taches supplémentaires en diffraction des électrons lents.
De nombreux diagrammes de diffraction des électrons lents (D. E. L.) contiennent des taches supplémentaires qui peuvent correspondre à un grand nombre d'arrangements atomiques différents. Pour l'instant la D. E. L. ne peut donner d'information que sur la périodicité latérale de l'arrangement atomique mais ne permet pas la détermination de la position des atomes dans la maille parallèlement et perpendiculairement à la surface. De telles informations doivent être obtenues à partir d'autres expériences, parmi lesquelles la spectroscopie des électrons Auger et les mesures de travail de sortie sont particulièrement utiles. L'état actuel de la compréhension de l'origine des taches supplémentaires à partir de ces techniques est illustré par deux exemples : un diagramme simple avec taches supplémentaires, celui du W (110)-p (2x1) — 0, et un diagramme complexe avec taches supplémentaires, celui de Si (111) — 7 x 7.Bauer Ernst. The origin of extra spots in low electron diffraction. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 94, 3, 1971. Réunion annuelle de l'Association Française de Cristallographie Grenoble, 25-27 mai 1970
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Growth, reaction and nanowire formation of Fe on the ZnS(100) surface
Full text linkX-ray photoelectron emission microscopy (XPEEM) was used in combination with other microscopic and spectroscopic techniques to follow the surface development of an aluminum brazing sheet during heating. The studied aluminum alloy sheet is a composite material designed for vacuum brazing. Its surface is covered with a native aluminum oxide film. Changes in the chemical state of the alloying elements and the composition of the surface layer were detected during heating to the melting temperature. It was found that Mg segregates to the surface upon heating, and the measurements indicate the formation of magnesium aluminate. During the heating the aluminum oxide as well as the silicon is observed to disappear from the surface. Our measurements is in agreement with previous studies observing a break-up of the oxide and the outflow of the braze cladding onto the surface, a process assisted by the Mg segregation and reaction with surface oxygen. This study also demonstrates how XPEEM can be utilized to study complex industrial materials.Copyright IOP Publishing. This is the authors' final, peer-reviewed manuscript. Man, Ka Lun, Pavlovska, Anastassia, Bauer, Ernst, Locatelli, Andrea, Mentes, Tevfik O., Nino, Miguel A., Wong, George K. L., Sou, Iam Keong, & Altman, Michael S. (2014). Growth, reaction and nanowire formation of Fe on the ZnS(100) surface. JOURNAL OF PHYSICS-CONDENSED MATTER, 26(31), 0-0. http://dx.doi.org/10.1088/2053-1591/3/10/106506. The final version as published can be viewed online at http://dx.doi.org/10.1088/0953-8984/26/27/31500
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