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  • 1985-1989  (5)
Materialart
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of low temperature physics 61 (1985), S. 155-169 
    ISSN: 1573-7357
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The surface tension of liquid4He was measured by means of surface-wave resonance, and the relative variation showed excellent agreement with that previously obtained by a precise capillary-rise method. The absolute value of the surface tension at absolute zero was measured as 354.4±0.5 mdyne/cm, 6% smaller than the previous value. The surface energy associated with the Bose-Einstein condensate wave function was found to dominate the surface tension in the superfluid phase. The condensate fraction other than in the vicinity of the λ point was estimated asn 0(0)-n 0(T)=A(T/T λ)α, withn 0(0)=0.125±0.025,A=0.177±0.047, and α=5.07±0.17.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of low temperature physics 63 (1986), S. 535-551 
    ISSN: 1573-7357
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The attenuation of sound was measured in3He-4He mixtures with3He concentrations ranging from 2.89 to 8.03% at pressures of 10 and 20 bar. The quasiparticle interaction potentials were then determined at each pressure by analyzing the sound attenuation data. The superfluid transition temperature of3He and other properties in the mixtures were then estimated from the interaction potentials.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Journal of low temperature physics 63 (1986), S. 129-137 
    ISSN: 1573-7357
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The surface tension of liquid4He in the neighborhood of the λ transition temperature was measured with very high precision by the surface-wave resonance method. The derivative of the surface tension with respect to temperature decreases by 21.1±0.8 mdyn/cm K as the temperature is increased from Tλ − 20 mK to Tλ + 20 mK. The regular part of the surface tension near Tλ is considered to consist of two parts, a ripplon contribution σR and a “bulk” contribution σB. In the present analysis, the singular part exists only below Tλ, and is proportional to (Tλ − T)1.3±0.1. This behavior seems to be related to the Bose-Einstein condensate or the superfluid density.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of low temperature physics 63 (1986), S. 495-506 
    ISSN: 1573-7357
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The surface tension of liquid3He and4He was measured near the gas-liquid critical points in the reduced temperature range 3×10−4〈t〈2×10−1, where t ≡ (T c −T)/T c . The critical exponents were found to be μ3=1.289±0.015 for3He and μ4=1.306±0.017 for4He. These values are very close to those for classical liquids, and are consistent with the value of 1.28 predicted by Widom, but are apparently different from the exponents previously obtained for liquid helium isotopes, which are near unity. The critical coefficients show good agreement with the quantum-corrected corresponding states theory for the Lennard-Jones 6–12 potential discussed by Young. The interface thickness is deduced from Widom's theory to bed=d 0t−v′ withd 30=0.14±0.03nm and v′3=0.57±0.04 for3He, andd 40=0.37±0.07 nm and v′4=0.58±0.01 for4He.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of low temperature physics 59 (1985), S. 291-304 
    ISSN: 1573-7357
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The surface tension of liquid3He was measured by determining the surface wave velocity in the temperature range from 0.32 to 3.02 K. The decrease of the surface tension from the value at 0 K can be described as 22.3T 2 mdyn/cm up to about 0.9 K and is quite different from that of4He. The extrapolated value to 0 K is 155.7±0.5 mdyn/cm. The data below 1.6 K were compared with Saam's model, where the surface tension is assumed to be given by the bulk free energy times the surface width and the quasi-two-dimensional free energy. Agreement between the data and the results calculated from the model is much improved if ripplons are taken into account. Data near the gas-liquid critical point, contrary to earlier results, show that the surface tension vanishes with a critical exponent of 1.24±0.05. This is in agreement with Widom's theory.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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