Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3007-3010 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The reaction between nitrogen gas and the series of R2Fe17 intermetallic compounds is studied by thermopiezic analysis on micron-size powders. Nitrogen diffusion in the range 300–550 °C can be represented by an activated interstitial diffusion process D=D0e−Em/kT with D0=1.95×10−10 m2 s−1 and an activation energy Em=0.81 eV. This stage of the nitrogenation reaction leads to the formation of R2Fe17N3−δ nitrides which have structures related to those of the parent compounds. Heating above about 800 °C leads to complete disproportionation of the compounds into a mixture of rare-earth nitride and iron.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 2058-2060 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A multiline visible emission spectrum, yielding "white" light, has been observed from a low-pressure Ba discharge. A five atomic level numerical model reproduces the observations qualitatively, suggesting that a low-pressure Ba discharge light source is capable of a significantly better color rendering than previously thought. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 4097-4101 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: This article reports on ultraviolet reflection–absorption spectroscopy of C6H6 molecules physisorbed on Ag, Cu, and Au surfaces. The electronic 1A1g→1B2u transition of C6H6 at wavelengths near 250 nm is observed. We model the system and obtain center frequencies, linewidths, and estimates of the oscillator strengths for the various vibronic absorptions. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3190-3197 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The decay rate of the Hg 61P1 level was measured as a function of cold spot temperature (Hg density) and buffer gas pressure in cylindrical, sealed fused silica cells. The decay rates were obtained using a time-resolved laser-induced 185 nm fluorescence experiment with multi-step excitation. Cold spot temperatures from 25 to 100 °C were studied. The Hg densities for this temperature range and with no buffer gas yield the lowest possible decay rates due to radiation trapping with partial frequency redistribution. Decay rates with argon buffer gas pressures of 3 and 30 Torr were also studied. The results are in agreement with published data from a discharge afterglow experiment. Monte Carlo simulations of radiation transport in the cells, including the effects of hyperfine and isotope structure, the effects of foreign gas broadening, and partial frequency redistribution are compared to the experimental data. Reasonably good agreement is obtained, however there is evidence of quenching of Hg 61P1 atoms in collisions with ground state Hg and Ar atoms. An analytic formula for the fundamental mode trapped decay rate of the 61P1 level, which is applicable over a substantial region of parameter space, was devised from the Monte Carlo results. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 731-737 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Numerical simulations of radiation transport in cylindrical geometry are used to determine the effect of radially symmetric inhomogeneities. The focus of this study are inhomogeneities such as may be produced by radial cataphoresis or temperature gradients in cylindrical glow discharges, i.e., a quadratic profile of absorbing atoms which has a minimum on the axis of the cylinder. A propogator function analysis of the Holstein–Biberman equation and a Monte Carlo simulation of resonance photon scattering are simultaneously used to examine three limiting cases of interest: (i) a pure Doppler broadened atomic lineshape, (ii) a pure Lorentz atomic lineshape produced by foreign gas broadening, and (iii) a pure Lorentz atomic lineshape produced by resonance collision broadening. The fundamental mode distribution of excited atoms, the fundamental mode trapped decay rate, and the volume-averaged escape rate for a homogeneous production rate per unit volume are calculated for each of these cases. The trapped decay rates are found to change modestly (depending upon lineshape) as the degree of inhomogeneity is increased, if the volume integral of the absorbing atom density remains fixed. Correction factors for the fundamental mode trapped decay rate are reported. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 45-48 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A highly sensitive absorption experiment for diagnosing glow discharge plasmas is described. This experiment is applicable from the VUV to the IR. A very stable Xe arc lamp is used as a source of continuum radiation. An echelle spectrometer equipped with a gated, image-intensified, charge-coupled device detector array is used to disperse and detect the continuum, with absorption features, after it has traversed the glow discharge. Digital subtraction is used to discriminate against the line emission from the glow discharge and detect only the continuum emission from the arc discharge. Estimates of the relative spectral radiances of glow and arc discharges suggests the subtraction technique is broadly applicable to glow discharge studies. A fractional absorption of 10−3 is detectable with a signal-to-noise ratio limited primarily by shot noise. A detection limit for excited Hg atoms of 7×109 cm−2 is demonstrated in a 400-mA Hg–Ar glow discharge. Further improvements in the experiment are proposed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1546-1554 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The gas temperature in a hot filament activated diamond chemical vapor deposition system is derived from the vacuum ultraviolet absorption spectrum of the H2 molecule. Curves of growth for the optically thick spectra are calculated using a Voigt line shape and published oscillator strengths in order to measure relative populations of H2 in various rotational and vibrational levels of the ground electronic state. The H2 vibrational levels are nearly in equilibrium. The gas temperature field is most strongly influenced by the substrate temperature. Heat conduction from the filament produces a large temperature gradient near the filament. Heat released or absorbed in gas phase hydrocarbon chemical reactions does not significantly affect the temperature field. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 66 (1944), S. 837-838 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3142-3150 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The methyl radical density, acetylene mole fraction, filament properties, and diamond growth rate and film quality are measured in a hot filament chemical vapor deposition system when C2H2 and H2 are used as the input gases. The methyl radical density and acetylene mole fraction depend greatly on the degree of filament surface poisoning. This poisoning prevents diamond growth due to a lack of hydrogen atoms and/or methyl radicals. Understanding the large influence of the filament surface catalytic characteristics is important for developing a gas phase model of this system. The results obtained with C2H2 and H2 as the input gases are compared to those obtained with CH4 and H2 as the input gases. Under conditions when the filament surface is not poisoned, the methyl radical concentrations are similar when either C2H2 and H2 are the input gases or when CH4 and H2 are the input gases.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7523-7528 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: This investigation focuses on low-pressure S2 molecular rf discharges for use as diffuse radiators. Cylindrical fused silica S2–Ar and S2–Ne lamps have been tested at 13.56 MHz and the absolute radiative efficiencies have been measured. The radiation is emitted primarily between 2800 and 3500 A(ring). The UV radiative efficiencies were studied as a function of input power, buffer gas pressure, discharge radius, and applied external cooling. The maximum observed efficiency for a low power density, diffuse rf discharge is 7%. The measured UV efficiencies of the 13.56 MHz discharges are somewhat lower than those of low-pressure S2–Ar dc discharges. A reentrant lamp design has been tested as well and no improvements in efficiency were observed. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...