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  • Digitale Medien  (10)
  • 78.70  (5)
  • Polymer and Materials Science  (3)
  • professional development  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 13 (1977), S. 365-369 
    ISSN: 1432-0630
    Schlagwort(e): 78.70
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The S-parameter, introduced by MacKenzie et al., is now widely used to describe annihilation gamma-ray lineshapes recorded with Ge(Li) spectrometers. This paper discusses four descriptive parameters, their statistical properties and their sensitivity to positron trapping.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 19 (1979), S. 149-152 
    ISSN: 1432-0630
    Schlagwort(e): 78.70 ; 66.30 F
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The activation energy for self-diffusion in chromium is found to be 3.51±0.13 eV from positron trapping measurements. The 4.51 eV activation energy seen in tracer diffusion work is therefore ascribed to divacancies, theQ 2/Q 1 ratio being typical of the bcc refractory group. The positron data give 0.55 for the ratioH 1v M /H 1v F of vacancy migration and formation energies, in agreement with quenching data for tungsten.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 19 (1979), S. 269-273 
    ISSN: 1432-0630
    Schlagwort(e): 78.70
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The monovacancy formation energy of Co is measured as 1.91 eV from a trapping model analysis of theT-dependence of the lineshape parameter. Previously discussed linear relationships between trapping threshold temperature and monovacancy parameters are refined; these relationships can now be regarded as well-established.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 16 (1978), S. 29-34 
    ISSN: 1432-0630
    Schlagwort(e): 78.70
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The Doppler broadened lineshape is measured as a function of temperature for iron and vanadium; vacancies produce a strong trapping effect in γ-Fe, but a weak effect in V. Threshold temperaturesT t for trapping are 1280±25 and 1370±30 K. Empirical linear relationships betweenT t , self-diffusion energyQ SD and monovacancy formation energyH 1v F are discussed and used to determineH 1v F values for γ-Fe and V.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 21 (1980), S. 19-24 
    ISSN: 1432-0630
    Schlagwort(e): 78.70
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Errors caused by instrumental instabilities in annihilation photon energy spectrometers can be much larger than statistical errors. The performance of a typical spectrometer is investigated in detail and both empirical and theoretical approaches to correcting data for residual fluctuations are examined.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 2009-2021 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effects of water-soluble and monomer-soluble impurities on the kinetics of emulsion polymerization of monomers following Case II kinetics (e.g., styrene) are investigated. Experimental studies reveal that impurities can have an appreciable effect on both polymer particle nucleation and growth. These effects are shown to be well predicted by a mathematical model.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    International journal of technology and design education 10 (2000), S. 105-123 
    ISSN: 1573-1804
    Schlagwort(e): primary school teaching ; professional development ; technology education
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Kunstgeschichte , Pädagogik , Technik allgemein
    Notizen: Abstract The purpose of this study was to investigate areas of significance which were related to the understanding of technology and technology education, identified by teachers introducing the key learning area, technology, into their primary school classrooms for the first time. Working from Australia's national document on technology education, A Statement on Technology for Australian Schools (Curriculum Corporation, 1994), two teachers wrestled with how to fit this new curriculum area into their current classroom programs, their understandings of technology as a phenomenon and with their beliefs about teaching and learning in general. The study showed that the teachers made sense of technology education as it related to, from their perspectives, ideas about and aspects of primary school classrooms with which they felt comfortable. Implications for professional development include the need to acknowledge and value the prior experiences and understandings of primary teachers. The challenge for teachers in implementing technology education is gaining a conceptualisation of the learning area, which in some respects, is very like other more familiar learning areas in the primary curriculum, but in many other respects, unique.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    International journal of technology and design education 10 (2000), S. 105-123 
    ISSN: 1573-1804
    Schlagwort(e): primary school teaching ; professional development ; technology education
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Kunstgeschichte , Pädagogik , Technik allgemein
    Notizen: Abstract The purpose of this study was to investigate areas of significance which were related to the understanding of technology and technology education, identified by teachers introducing the key learning area, technology, into their primary school classrooms for the first time. Working from Australia's national document on technology education, A Statement on Technology for Australian Schools (Curriculum Corporation, 1994), two teachers wrestled with how to fit this new curriculum area into their current classroom programs, their understandings of technology as a phenomenon and with their beliefs about teaching and learning in general. The study showed that the teachers made sense of technology education as it related to, from their perspectives, ideas about and aspects of primary school classrooms with which they felt comfortable. Implications for professional development include the need to acknowledge and value the prior experiences and understandings of primary teachers. The challenge for teachers in implementing technology education is gaining a conceptualisation of the learning area, which in some respects, is very like other more familiar learning areas in the primary curriculum, but in many other respects, unique.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 105-108 
    ISSN: 0142-2421
    Schlagwort(e): ESD ; Si(100) ; electron-stimulated desorption ; silicon ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: We have studied digermane-covered Si(100) using electron-stimulated desorption (ESD). Estimates are presented for the total H(a) ESD removal cross-section for digermane-exposed Si(100) substrates at 85 K using electrons incident at 150 eV energy. It is found that electron-enhanced deposition of Ge occurs only when physisorbed digermane is present. Auger electron spectroscopy provided the means for determining the relative amounts of germanium adsorbed on the Si(100) surface following digermane exposures, electron irradiation and surface reconstruction. It is found that two coverage regimes are important: initial dosing of digermane on Si(100) at 85 K results in overlayers consisting of both physisorbed digermane and chemisorbed GeHx(a) (x=1, 2 or 3) species; and short anneals to 200 K following exposure of the Si(100) surface at 85 K lead to the presence of only chemisorbed GeHx(a). The two coverage regimes exhibit different ESD behavior. Two kinetic energy distribution (KED) peaks are seen when physisorbed digermane is present, and only one when it is absent. The ESD signal decay curves obtained from the two surfaces are also different: the presence of physisorbed digermane results in a two-component exponential signal decay; the absence of the physisorbed species results in a single-exponential decay. The total H removal cross-section from the physisorbed digermane overlayer was determined to be σ∽1.4×10-15 cm2, while that from Si(100) with only adsorbed GeHx present was found to be σ∽2.6×10-16 cm2. Our results suggest that adsorbed GeHx(a) species remain intact on the surface even when the Si(100) substrate is annealed to 200 K, indicating that hydrogen migration from surface GeHx(a) to Si surface sites does not occur at 200 K. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 97-104 
    ISSN: 0142-2421
    Schlagwort(e): ammonia ; Pt ; adsorption ; electron irradiation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The effects of electron impact on ammonia-covered Pt(111) have been studied using temperature-programmed desorption (TPD) and electron-stimulated desorption (ESD). For coverages below one monolayer, ammonia adsorbs on the surface in two distinct TPD states: the α-state is broad and desorbs over the temperature range 150-350 K, and the β-state appears as a sharper peak at 150 K. The β-state was seen to be damaged by electron-beam impact much more readily than the α-state, resulting in the formation of atomically adsorbed N on the surface. The mass 28 recombinative nitrogen desorption TPD peak appearing at 550 K exhibited second-order desorption kinetics, further confirming the presence of atomically adsorbed nitrogen. The ESD kinetic energy distributions (KEDs) were obtained for m/e=1 amu, which exhibited broad peaks generally. The H+ KEDs were analyzed using empirical curve fits, with the resulting conclusion that the H+ KEDs contain contributions from at least three different hydrogen-containing surface species. We believe that these three H+ KED peaks are due to ESD from adsorbed NH3, NH2 and H. The ESD cross-section for NH3 removal was measured in three different ways, all of which were found to be in general agreement, and which gave an averaged cross-section value of Qtot=4×10-17 cm2. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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