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  • 1
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A significant increase in the ultraviolet laser-damage threshold of CaF2 (1 1 1) single-crystal surfaces after surface finishing by chemomechanical polishing (CMP) with colloidal silica has been demonstrated as compared to conventional mechanical-abrasive polishing (MAP). It was shown that CMP yields an up to 12-fold increase of the damage threshold fluence up to Fth = 30 J cm−2 for 1-on-1 nanosecond pulses of 248 and 193 nm excimer laser irradiation. Even after 5-on-1 irradiations, the damage threshold remains as high as Fth = 15 J cm−2 in the case of CMP. For both polishing procedures, the change in dielectric surface properties has been characterized by means of scanning electron microscopy (SEM) using electron beam-induced charge-up phenomena. These were mainly detected by the variation of emitted secondary electron (SE) yield δSE depending on the primary electron (PE) energy. Two kinds f charge-up phenomena were employed: (i) the onset or vanishing of statistically fluctuating SE yield bursts during slow-scan imaging (“stripe pattern” method), and (ii) the temporal decay of the electron beam-induced charge-up inside an electrically conducting mask (charge decay method). Both these phenomena disappeared after CMP. It is concluded that this disappearance results from removing the subsurface damage layer which is typical of MAP.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of ornithology 96 (1955), S. 352-359 
    ISSN: 1439-0361
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Surfaces of fluoride crystals, fractured by a single excimer laser pulse and then covered by a thin conductive layer, are imaged by scanning electron microscopy in the low-voltage secondary electron mode. As a result of charging, at lower primary electron energies a contrast enhancement can be obtained for surface fragments that are no longer tightly attached to the crystal. This differs from high-energy ((approximately-greater-than)10 keV) imaging which only yields topographic contrasts and allows the analysis of the fractured structure by edge and shadowing effects. Even contrast inversion from positive to negative charging of an entire fragment can be achieved, depending on the primary electron energy. It is shown that this effect can be utilized to discriminate between fragments with a good mechanical contact to the bulk and partially detached ones by systematically studying the contrast as a function of electron energy and specimen inclination. © 1996 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 31 (1992), S. 3023-3025 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of ornithology 96 (1955), S. 428-436 
    ISSN: 1439-0361
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 7
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Ablation thresholds and damage behavior of cleaved and polished CaF2(111) surfaces produced by single shot irradiation with 248nm/14ns laser pulses have been investigated using the photoacoustic mirage technique and scanning electron microscopy. The standard polishing yields an ablation threshold of typically 20 J/cm2. When surfaces are polished chemo-mechanically the threshold is raised to 43 J/cm2. Polishing by diamond turning leads to intermediate values around 30 J/cm2. Cleaved surfaces possess no well-defined damage threshold. The damage topography of conventionally polished surfaces shows ablation of flakes across the laser heated area with cracks along the cleavage planes. In the case of chemo-mechanical polishing only a few cracks appear. Diamond turned surfaces show small optical absorption, but cracks and ablation of tiles. The origin of such different damage behavior is discussed.
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  • 8
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Elektronenstrukturen der Tetraedersysteme CrO 4 2− , VO 4 3− und TiCl4 werden an Hand halbquantitativer LCAO-MO Rechnungen diskutiert.
    Abstract: Résumé Discussion des structures électroniques des systèmes tétraédriques CrO 4 2− , VO 4 3− et TiCl4 sur la base de calculs semi-quantitatifs LCAO MO.
    Notes: Abstract The electronic structures of the tetrahedral systems CrO 4 2− , VO 4 3− and TiCl4 are discussed on the basis of semiquantitative LCAO MO calculations.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 11 (1968), S. 8-25 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Elektronenstruktur des Permanganations wurde mit einer halbquantitativen LCAO-MO Methode ohne empirische Parameter behandelt. Die Zustandsfunktionen des Zentralatoms wurden variiert und der Einflu\ symmetrische Änderungen der BindungsabstÄnde untersucht. Um die Gegenwart von Kationen in Lösung und im Kristall zu simulieren, wurden daneben auch Rechnungen durchgeführt, bei denen einer stÄrkeren Elektronenanziehung durch die Liganden Rechnung getragen wird. Ferner wurde versucht, das Absorptionsspektrum von MnO 4 − auf Grund der vorausgesagten Bandenform und übergangsenergien zu deuten.
    Abstract: Résumé La structure électronique de l'ion permanganate est étudiée à l'aide d'une méthode LCAO MO semi-quantitative sans paramètres empiriques. La base d'orbitales atomiques pour l'ion central a été systématiquement variée et l'effet de changements symétriques des longueurs de liaison a été aussi examiné. Pour simuler la présence des cations dans la solution et dans le cristal on a fait des calculs dans lesquels la région autour des ligands était rendue plus attractive pour les électrons. Le spectre d'absorption de MnO 4 −1 est interprété à l'aide des prédictions sur les formes des bandes et les énergies de transition.
    Notes: Abstract The electronic structure of the permanganate ion has been investigated, using a semiquantitative LCAO MO method without empirical parameters. The atomic orbital basis set for the central ion has been varied systematically, and the effect of symmetric changes of bond distances has also been examined. In addition, calculations have been performed in which the regions around the ligands have been made more attractive for electrons, to simulate the presence of cations in solution and in the crystalline state. The electronic absorption spectrum of MnO 4 − has been tentatively assigned, on the basis of predicted band shapes and transition energies.
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  • 10
    ISSN: 1432-2242
    Keywords: Partial selfing ; Hardy-Weinberg proportions ; Gametic phase disequilibrium ; Cultivar identification ; Starch gel electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Samples of approximately 100 plants from each of 22 populations ofLolium perenne representing 15 cultivars, and from 13 populations ofLolium multiflorum representing six cultivars were scored for iso-zyme variants in five enzyme systems, PGI, GOT, ACP, PGM and 6-PGD. From the individual banding patterns a genetic interpretation of the variation was formulated and population studies of the resulting six polymorphic enzyme loci were performed. No strong indications of partial selfing was found since at four of the six loci,Pgi 2, Got 3, Pgm 1 andPgd 1, the genotypic proportions were in correspondence with the Hardy-Weinberg expectations. This indicated, further, that the genetical interpretations of the banding patterns might be correct. Deviations from Hardy-Weinberg proportions forAcp 1 andGot 2 indicated presumably selection working on the linkage group including these loci. Gametic phase disequilibrium was observed betweenPgi 2 andPgd 1 for populations of one cultivar. These results were discussed in relation to the variation expected within a cultivar.
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