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  • 2010-2014  (116)
  • 1985-1989  (47)
  • 1935-1939  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Line broadening, line shifting, and line coupling effects on N2–H2O stimulated Raman spectra (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5916-5925 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: In order to understand the influence of H2O on the stimulated Raman Q-branch spectra of nitrogen in combusting media, an exhaustive theoretical and experimental study has been carried out. Starting from a semiclassical model, particularly convenient at high temperature, the Q-line broadening and shifting coefficients have been calculated over a wide temperature range and for a large number of lines. Stimulated Raman Spectra (SRS) measurements have allowed us to test these calculated line broadening coefficients and thus establish the high accuracy of semiclassical values. The theoretical broadening coefficients have been inverted to deduce state-to-state rotational relaxation rates by using two types of fitting laws. A partial test of the resulting Q-branch profiles has been realized at moderate pressures leading to a discrimination between these two laws. Furthermore, the effect of rotational energy transfers on collisionally narrowed profiles at higher densities has been simulated and compared with the pure N2 case.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.457461
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  • 2
    Digitale Medien
    Digitale Medien
    Measurements and calculations of CO2 room-temperature high-pressure spectra in the 4.3 μm region (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 2944-2950 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Measurements of the absorption by pure CO2 in the 4.3 μm region are presented. They refer to the temperature of 291 K and densities in the 1–80 amagat range. Calculations based on the addition of Lorentzian contributions strongly overestimate the absorption since they do not account for line overlapping. The energy corrected sudden approximation (ECSA) is used to model line mixing within the impact approximation. The scaling parameters of this model are deduced from line-broadening data. This calculation strongly underestimates the absorption in the spectral region near the edges of the vibrational band, whereas it overestimates the absorption in the far wings of the lines. This is attributed to the impact approximation which does not account for the frequency dependence of the relaxation operator. This dependence is roughly determined from our results; it is in good qualitative agreement with the few corresponding available results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.455894
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  • 3
    Digitale Medien
    Digitale Medien
    Collisional broadening of rotation–vibration lines for asymmetric-top molecules. II. H2O diode laser measurements in the 400–900 K range; calculations in the 300–2000 K range (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 144-156 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Numerous comparisons between predictions of the model presented in part I of this paper and experimental H2O infrared linewidths are presented. It is shown that our model, contrary to those used up to now, gives accurate results for H2O room-temperature line broadening by O2 and Ar, and for high rotational quantum-number lines by N2. First accurate experimental widths and intensities of some H2O ν2-band lines in the 400–900 K temperature range are also presented. Detailed analysis of the data demonstrates the great influence of a "resonance overtaking'' mechanism. The latter results from the modifications of both the perturber rovibrational population distribution and kinetic energy with temperature; it strongly enhances the contributions of the collision-induced rotational transitions involving significant energy jumps. This mechanism is well accounted for by our model and quantitatively explains the unusually slow decrease of some linewidths with temperature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.452605
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  • 4
    Digitale Medien
    Digitale Medien
    Collisional broadening of CO2 IR lines. II. Calculations (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 2999-3006 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The ability of available theoretical models in describing broadening mechanisms is tested for the CO2–O2, CO2–CO2, and CO2–N2 systems. It is shown that the Anderson–Tsao–Curnutte theory is inaccurate since short-range forces can contribute significantly to broadening. We use the approach of Robert and Bonamy, but the usual expansion of the atom–atom potential to the fourth order around the intermolecular distance appears insufficient at short distances for these particular systems. We propose a better representation of the radial dependence of the atom–atom potential, while keeping the previous analytical expression of the cross section. Satisfactory results are obtained for both the rotational quantum number dependence of room-temperature CO2–O2, CO2–CO2, and CO2–N2 half-widths and the evolution of CO2–N2 broadening with temperature. It is shown that the isotropic part of the potential involved in the trajectory calculation must be coherently deduced from the atom–atom interaction potential.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.453941
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  • 5
    Digitale Medien
    Digitale Medien
    Collisional broadening of rotation–vibration lines for asymmetric-top molecules. III. Self-broadening case; application to H2O (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 2781-2789 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: A semiclassical theory of asymmetric-top molecule line broadening, developed in part I of this series of papers for linear perturbers, is extended to asymmetric-top perturbers. This model has been successfully applied in part II to the broadening of H2O lines by N2, O2, and Ar. The present applications to the self-broadening of H2O infrared and Raman lines in the 300–900 K range also show the quality of the model. Due to the high electrostatic forces involved in the H2O–H2O interaction, the short-range anisotropic potential has little influence. Nevertheless, the need for a modeling of the trajectory is demonstrated, mainly in the case of high rotational quantum number lines.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.453065
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  • 6
    Digitale Medien
    Digitale Medien
    Collisional broadening of rotation–vibration lines for asymmetric top molecules. I. Theoretical model for both distant and close collisions (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 4256-4267 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: A semiclassical theory of infrared linewidths in the gas, previously developed for linear molecules, is extended to asymmetric top molecules. It includes a satisfactory treatment of the close collisions and is consequently adapted to describe the temperature dependence of the linewidths, in particular in the combustion temperature range. Numerical applications to the water vapor perturbed by nitrogen, oxygen, and argon show strong different behaviors following the nature of the perturber. For oxygen and argon perturbers, the contribution of close collisions is the predominant mechanism of line broadening. The consistency of the theoretical model is evidenced by comparison with precise measurements for H2O–N2, –O2, and Ar at 300 K. Moreover, the calculated temperature dependence of the linewidths is compared with recent experimental data for H2O–Ar between 1300 and 2300 K.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.450047
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  • 7
    Digitale Medien
    Digitale Medien
    Isolation, Purification, and Characterization of Lipase Isoenzymes from a Technical Aspergillus niger Enzyme (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 50 (1985), S. 0 
    Details
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A qualitative screening revealed the occurrence of lipase, esterase, protease, amylase, endo-1,4-β-D-glucanase, xylanase, pectinmethylesterase, polygalacturonase, catalase, β-D-glucosidase and β-D-galactosidase activities in the technical Aspergillus niger enzyme under study (Lipase 2212 D, Röhm). The isolation and purification of lipolytic activities were performed by combination of DEAE-Trisacryl M ion exchange chromatography, Sephadex G 50 gel filtration and hydrophobic chromatography using Phenylsepharose CL-4B. The individual purification steps were checked by specific enzyme visualization in ultrathin agar gels after ultrathin-layer isoelectric focusing (UIEF). Two UIEF homogeneous lipase isoenzymes (I and II) were isolated and characterized by the following parameters: isoelectric points (I: 4.0; II. 3.5); molecular weights (I: 31000 daltons; II: 19000 daltons); carbohydrate contents (I: 6%; II: 9%) and compositions; pH optima (I, II: 5-6); substrate specificities and various effectors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2621.1985.tb10574.x
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  • 8
    Digitale Medien
    Digitale Medien
    On nocturnal wind shear with a view to engineering applications (1986)
    Springer
    Boundary layer meteorology 37 (1986), S. 215-227 
    Details
    ISSN: 1573-1472
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Wind shear data from 14 clear nights with low-level jet development are analysed up to heights of 200 m. Temporal variations of the magnitude of the shear vector and of the power-law exponent p are shown. The frequencies of occurrence of maximum shear and of p are examined and the effect of the product of geostrophic surface wind speed and mean layer temperature gradient on the shear is investigated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00122985
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  • 9
    Digitale Medien
    Digitale Medien
    A measurement of muon pair production ine + e − annihilation at centre of mass energies 35.0≤ $$\sqrt s $$ ≤46.8 GeV (1988)
    Springer
    The European physical journal 40 (1988), S. 163-170 
    Details
    ISSN: 1434-6052
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The reactione + e −→µ+µ− has been studied at centre of mass energies between 35.0 and 46.8 GeV using the TASSO detector at PETRA. We present measurements of the forward-backward charge asymmetry (A μμ) and cross section σμμ for this reaction at three energies. At 35.0 GeV we obtain a cross section relative to the QED prediction ofR μμ=σμμ/σo=0.932±0.018±0.044 andA μμ=(−10.6 −2.3 +2.2 ±0.5)%. At 38.3 GeV we findR μμ=0.951±0.072 −0.057 +0.063 andA μμ=(+1.7 −8.6 +8.5 ±0.5)%. At 43.6 GeV we measureR μμ=0.921±0.037±0.055 andA μμ=(−17.6 −4.3 +4.4 ±0.5)%. Our results are in good agreement with the predictions of the standard model. Including previous TASSO data we present improved determinations of muonic electroweak parameters. We also report on lower limits of possible contributions from contact interactions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01555879
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  • 10
    Digitale Medien
    Digitale Medien
    A measurement of the τ lifetime (1988)
    Springer
    The European physical journal 39 (1988), S. 331-337 
    Details
    ISSN: 1434-6052
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have reconstructed 695 three-track τ decay vertices using a high resolution drift chamber close to the interaction point. From the distribution of decay lengths we measure the lifetime to be (3.06 ±0.20±0.14)×10−13 s. Using this result we find that the ratio of charged weak coupling constant for the τ to that of the μ,G τ/G μ=0.967±0.040 consistent with the concept of lepton universality.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01548282
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