Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Experimental determination of the transmission factor for the Omicron EA125 electron analyzer (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 3634-3639 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article a study of the transmission factor of the Omicron EA125 analyzer equipped with the universal lens is presented. The procedure is based on a model by Cross and Castle [J. Electron Spectrosc. Relat. Phenom. 22, 53 (1981)] and is applicable to every spectrometer which can be operated in the constant analyzer energy (CAE) and in the constant retarding ratio measuring mode. The advantage of the method is its independence on the sample and on the inelastic mean free path of the electrons. We find that the transmission factor for the CAE mode is proportional to Ekin−1 for most measuring setups. This dependence is predicted by theory for an ideal analyzer. Deviations from this behavior are observed if the retarding ratio for a given kinetic energy is too small. The limit value of the retarding ratio for ideal behavior, i.e., an Ekin−1 transmission factor, depends on the analyzer entrance slit aperture which has been selected. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1313798
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Characterization of thin film electron emitters by scanning anode field emission microscopy (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 768-780 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Scanning anode field emission microscopy is used to map the electron emission current I(x,y) under constant anode voltage and the electron extraction voltage V(x,y) under constant emission current as a function of tip position on carbon based thin film emitters. The spatially resolved field enhancement factor β(x,y) is derived from V(x,y) maps. It is shown that large variations in the emission site density (ESD) and current density can be explained in terms of the spatial variation of the field enhancement β(x,y). Comparison of β(x,y) and I(x,y) shows that electron emission currents are correlated to the presence of high aspect ratio field enhancing structures. We introduce the concept of field enhancement distribution f(β), which is derived from β(x,y) maps to characterize the field emission properties of thin films. In this context f(β)dβ gives the number of emitters on a unit surface with field enhancement factors in the interval (β,β+dβ). It is shown experimentally for the carbon thin film emitters investigated that f(β) has an exponential dependence with regard to the field enhancement factor β. The field enhancement distribution function f(β) can be said to give a complete characterization of the thin film field emission properties. As a consequence, the emitted current density and ESD can be optimized by tuning f(β) of the emitting thin film. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1379559
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Creation of a conductive surface layer on polypropylene samples by low-pressure plasma treatments (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5695-5701 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polypropylene (PP) samples were treated in an electron cyclotron resonance plasma with several gases and under different treatment conditions (pressure, treatment time, rf potential). The surfaces were chemically characterized in situ by x-ray photoelectron spectroscopy (XPS). Changes in the electrical resistance of the surface layer were analyzed by four points measurements. Noble gas plasma treatments led to a great decrease (ten orders of magnitude) of the resistance, whereas reactive gas plasma treatments induced no modification of the resistance. Taking into account that the treated layer corresponds to the ion penetration depth, an estimation gives 0.1 Ω cm for the bulk resistivity of He plasma treated PP. For noble gases, this value depends on the plasma gas and on the ion kinetic energy. The resistance decrease is explained by a dehydrogenation and an increase of carbon–carbon bonds. During reactive gas plasma treatments, the incorporation of new chemical species prevents this graphitization. Correlations of the resistance with XPS measurements and comparisons with literature on high energetic ion treatments allow a better understanding of the effects of the plasma treatment. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359211
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Plasma modification of polymethylmethacrylate and polyethyleneterephthalate surfaces (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 887-892 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Noble gas (He,Ar,Xe) and reactive gas (O2,N2) plasma treatments of polymethylmethacrylate (PMMA) and polyethyleneterephthalate (PET) surfaces were performed in an electron-cyclotron-resonance plasma. In situ surface analysis by x-ray photoelectron spectroscopy reveals well-defined surface compositions. From these measurements it is concluded that, independently of the plasma gas, the plasma ions easily decompose the ester group in PMMA in its constituents by an ion-electron recombination process, while in PET the ester decomposition is less pronounced. The difference is ascribed to the presence in PET of a phenyl ring, which protects the ester group by various mechanisms. The study of O2 plasma treatments shows that the equilibrium between the depletion of oxygen and the incorporation of the reactive species in the polymer surface is solely determined by the ion current. The plasma-polymer interactions are qualitatively explained by simple rules of intermolecular forces and ion-electron recombination phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357765
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Collective emission degradation behavior of carbon nanotube thin-film electron emitters (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1036-1038 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The current-induced emission degradation of a carbon nanotube (CNT) thin-film electron emitter is studied under constant emission current for different current levels, using a scanning anode field emission microscope. A permanent emission degradation is observed for emission currents higher than 300 nA per CNT and is associated with resistive heating at the CNT–substrate interface for the sample under investigation. A second field-induced emission degradation mechanism, associated with the removal of CNTs from the substrate, is also reported. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1392982
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Vacuum arc discharges preceding high electron field emission from carbon films (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 476-478 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Field emission measurements on chemical vapor deposition diamond and laser ablated a-C films show an activation step after reaching a certain critical electric field. At this field a vacuum arc of some hundred ns duration initiates. While high current arcing leads to the evaporation of the spot surface melting, amorphization or cracking of the film is encountered for lower currents. In any case, much higher electron emission can be observed after this activation procedure due possibly to tip formation resulting in an electric field enhancement. By using a 1 GΩ resistance the discharge current can be limited nevertheless, an activation is observed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118145
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Field emitted electron energy distribution from nitrogen-containing diamondlike carbon (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2253-2255 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on energy resolved field emission measurements of 0.3 μm thick nitrogen containing diamondlike carbon (DLC). The film used in this study was deposited by filtered arc deposition onto a highly p-doped Si(100) wafer. The film showed homogeneous field emission over the entire wafer area with an onset field for 1 nA emission current of 20–25 V/μm. The energy resolved field emission measurements were carried out with an applied electric field of 20–22 V/μm. The field emitted electrons originate from the Fermi energy, indicating that no field penetration occurs. The energy distribution has a FWHM of 0.63 eV at an applied field of 21 V/μm. The spectra could be deconvoluted using standard tunneling theory. The results of the deconvolution indicate an electric field strength of 6500 V/μm at the emission site. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120042
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Acute toxicity of bicyclic phosphorus esters (1976)
    Springer
    Archives of toxicology 35 (1976), S. 149-152 
    Details
    ISSN: 1432-0738
    Keywords: Bicyclic phosphorus esters ; 4-Ethyl-1-phospha-2,6,7-trioxabicyclic (2.2.2)-octane-1-oxide ; 4-Ethyl-1-phospha-2,6,7-trioxabicyclo (2.2.2)-octane ; Acute toxicity ; combustion products-polyurethane ; Bicyclische Phosphorester ; 4-Äthyl-1-phospha-2,6,7-trioxabicyclo (2,2,2) octan-1-oxid ; 4-Äthyl-1-phospha-2,6,7-trioxabicyclo (2,2,2) octan ; Akute Toxicität ; Verbrennungsprodukte-Polyurethan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die akute Toxicität von 4-Äthyl-1-phospha-2,6,7-trioxabicyclo-(2,2,2)-octan-1 -oxid und 4-Äthyl-1-phospha-2,6,7-trioxabicyclo-(2,2,2)-octan wurde bei verschiedenen Tierarten mittels verschiedener Applikationsarten bestimmt. Die Verbindungen stimulieren die Aktivität des Zentralnervensystems und sind hoch toxisch. Sie zeigen keine kumulativ-toxischen Wirkungen. Das Vorhandensein des bicyclischen Phosphatesters in den Verbrennungsprodukten von spezifischen Polyurethan-Hartschäumen wird diskutiert. Es wird in Frage gestellt, ob dieses Produkt in einer Brandsituation eine zusätzliche Gefahrenquelle darstellt.
    Notes: Abstract The acute toxicity of 4-ethyl-1-phospha-2,6,7-trioxabicyclo (2.2.2) octane-1-oxide and 4-ethyl-1-phospha-2,6,7-trioxabicyclo (2.2.2) octane has been determined by different routes of application in various species of animals. The compounds stimulate the activity of the central nervous system and are highly toxic. They showed no toxic cumulative effects. The presence of the bicyclic phosphate ester in the combustion products of specific rigid polyurethane foams is dicussed. The question is raised whether there may be an additional hazard caused by this combustion product in a real fire situation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00372769
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Thermal and Chemical Properties of a Glass in the SiO2-CaO-F System for Dental Applications (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 1009-1018 
    Details
    ISSN: 1572-8943
    Keywords: calcium fluoride silicate ; calcium release ; crystallization ; dental application
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystallization behaviour of a glass in the SiO2-CaO-F system was analyzed using differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Three crystalline phases were detected according to ICDD patterns. The first phase formed at 583°C was identified as CaF2. The morphology was spherulitic with a diameter of approximately 100 nm. The second phase was formed at 664°C. It was identified as calcium fluoride silicate ‘Ca2SiO2F2’ (ICDD 35-0002). SEM investigation showed that the crystals were spherulitic with a diameter smaller than 100 nm. The crystals were precipitated in the volume of the glass and homogeneously distributed. As a third phase, cristobalite crystallized at 895°C. The simultaneous release of calcium and fluorine ions from the vitreous glass in lactate buffer solution at pH 4.0, simulating an acidic oral environment, was investigated using X-ray photoelectron spectroscopy (XPS). The release of calcium and fluorine ions is of special interest for dental applications. The atomic ratios of the components Si, Ca and F at the glass surface after different leaching periods were determined. In order to investigate the leaching process, concentration profiles were measured using ion beam sputtering with Ar+ -ions. The dependence of the atomic ratios of Si, Ca and F on the sputter time was determined in order to measure the depth of the leaching layers. Most probably, the release of calcium and fluoride was controlled by a surface layer rich in calcium and flourine ions which dissolved with increasing leaching time. After 2 min leaching, a fluoride-rich surface layer measuring approximately 10 nm was detected. The atomic ratios of Si, Ca and F were different from the bulk composition ratios in a surface reaction layer of 800 nm thickness. After 30 min leaching time, a calcium- and fluoride-rich surface layer approximately 50 nm thick was formed. The bulk composition was reached at a depth of approximately 500 nm. The main component in the surface layer, after 12 days leaching in acidic environment, was silicon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010132429974
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...