Surface tension of pure liquid helium isotopes

Dyugaev, A. M.; Grigoriev, P. D.

doi:10.1134/1.1633319

Cited by 7 publications

(40 citation statements)

References 12 publications

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“…These excitations, called surfons, are He atoms in a quasistationary discrete quantum energy level above the liquid helium surface [48][49][50]. The state is formed by the combination of the van-der-Waals attractive potential of the bulk helium and the hard-core repulsion between He atoms.…”

Section: B Scattering By Surfonsmentioning

confidence: 99%

Neutrons on a surface of liquid helium

et al. 2016

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We investigate the possibility of ultracold neutron (UCN) storage in quantum states defined by the combined potentials of the Earth's gravity and the neutron optical repulsion by a horizontal surface of liquid helium. We analyse the stability of the lowest quantum state, which is most susceptible to perturbations due to surface excitations, against scattering by helium atoms in the vapor and by excitations of the liquid, comprised of ripplons, phonons and surfons. This is an unusual scattering problem since the kinetic energy of the neutron parallel to the surface may be much greater than the binding energies perpendicular. The total scattering time constant of these UCNs at 0.7 K is found to exceed one hour, and rapidly increasing with decreasing temperature. Such low scattering rates should enable high-precision measurements of the scheme of discrete energy levels, thus providing improved access to short-range gravity. The system might also be useful for neutron β-decay experiments. We also sketch new experimental concepts for level population and trapping of UCNs above a flat horizontal mirror.

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Section: B Scattering By Surfonsmentioning

confidence: 99%

Neutrons on a surface of liquid helium

et al. 2016

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“…These surface bound states determine the value and the temperature dependence of the surface tension of a 3 He-4 He mixture [9]. Recently, similar bound states were proposed [10] in pure He isotopes and were called surface level atoms (SLA). These SLAs may be considered a new type of surface excitations of liquid He in addition to ripplons.…”

Section: Introductionmentioning

confidence: 99%

“…These SLAs may be considered a new type of surface excitations of liquid He in addition to ripplons. It is SLAs rather than ripplons that determine the temperature dependence of the surface tension of both liquid helium isotopes and explain longstanding puzzles [10,11] in this temperature dependence [10]. In particular, SLAs explain the exponential temperature dependence of the surface tension of liquid 3 He at temperatures below 0.15 K. After taking SLAs into account, a very good agreement (up to 0.1%) can be reached between theory and experiment on the temperature dependence of the He surface tension in a large temperature interval [10].…”

Section: Introductionmentioning

confidence: 99%

“…However, SLAs can be considered phenomenologically, similarly to the quantum states of helium atoms localized above the liquid helium surface [10]. SLAs may also propagate in the surface plane and have the quadratic dispersion where k is the 2D momentum of SLAs along the surface.…”

Section: Introductionmentioning

confidence: 99%

“…If we take the energies of He atoms in vacuum to be zero, = 0, the chemical potentials are = -7.17 K and = -2.5 K as T 0, while the energies of SLAs, as suggested by the temperature dependence of the surface tension [10], are 2 (4) Therefore, at sufficiently low temperatures, the concentration of SLAs becomes exponentially higher than the He vapor concentration, and the influence of SLAs on the properties of surface electrons becomes more important than the influence of He vapor. Thus, the scattering on the surface level atoms affects the mobility, the quantum decoherence time, and other properties of surface electrons.…”

Section: Introductionmentioning

confidence: 99%

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10.1007/s11447-008-2010-3

2010

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The temperature dependence of electron mobility is examined. We calculate the contribution to the electron scattering rate from the surface level atoms (SLAs), proposed in [10]. This contribution is substantial at low temperatures T < 0.5, when the He vapor concentration is exponentially small. We also study the effect of depopulation of the lowest energy subband, which leads to an increase in the electron mobility at high temperature. The results explain certain long-standing discrepancies between the existing theory and experiment on electron mobility on the surface of liquid helium.

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