Related papers: Metastable helium molecules as tracers in superflu…
Helium is recognized as a model system for the study of phase transitions. Of particular interest is the superfluid phase in two dimensions. We report measurements on superfluid helium films adsorbed on the surface of a suspended carbon…
A theory of thermoelectric phenomena in superfluid $^4He$ is developed. It is found an estimation of the dipole moment of helium atom arising due to electron shell deformation caused by pushing forces from the side of its surrounding atoms.…
Vortex filament model has become a standard and powerful tool to visualize the motion of quantized vortices in helium superfluids. In this article, we present an overview of the method and highlight its impact in aiding our understanding of…
Decoherent quantum equations of motion are derived that yield the trajectory of an open quantum system. The viscosity of superfluid Lennard-Jones helium-4 is obtained with a quantum stochastic molecular dynamics algorithm. The momentum…
The experimental investigation of superfluid turbulence in 3He-B is generally not possible with the techniques which have been developed for 4He-II. We describe a new method by which a transient burst of turbulent vortex expansion can be…
High resolution spectroscopy of doped molecules in 4He nano-droplets and clusters gives a signature of superfluidity in microscopic system, termed as microscopic superfluidity. Ro-vibrational spectrum of 4HeN-M clusters is studied with the…
We derive the hydrodynamic equations of motion of solid and supersolid 4He, that describe the collective modes of these phases. In particular, the usual hydrodynamics is modified in such a way that it leads to the presence of a propagating…
The helium dimer in its metastable triplet state is a promising candidate to be the first laser-cooled homonuclear molecule. An ultracold gas of He$_2^*$ would enable a new generation of precision measurements to test quantum…
The flow velocity of solid 4He through a porous membrane frozen into a crystal has been measured in the temperature interval 0.1 - 1.8 K. A flat capacitor consisting of a metalized plastic porous membrane and a bulk electrode is applied and…
We observe the formation of heaps of repulsive microspheres, created by flowing a colloidal microsphere suspension towards a flat-topped ridge placed within a quasi two-dimensional microfluidic channel. This configuration allows for both…
By using the glassy (helium-)fluid model and boundary perturbation method, we can obtain the velocity fields (as well as the flow rate; up to the second order) inside the wavy-rough cylindrical nanopores which are of the same size as those…
We have measured the temperature dependence of the time of flight of helium excimer molecules He2* in superfluid 4He and find that the molecules behave ballistically below 100mK and exhibit Brownian motion above 200 mK. In the intermediate…
Solid 4He has been created off the melting curve by growth at nearly constant mass via the "blocked capillary" technique and growth from the 4He superfluid at constant temperature. The experimental apparatus allows injection of 4He atoms…
The relaxation of photoexcited nanosystems is a fundamental process of light-matter interaction. Depending on the couplings of the internal degrees of freedom, relaxation can be ultrafast, converting electronic energy in a few fs, or slow,…
We explore experimentally the fluidization of vertically agitated PMMA spheres wetted by liquid $^4$He. By controlling the temperature around the $\lambda$ point we change the properties of the wetting liquid from a normal fluid (helium I)…
Pulsed (30 - 100 microseconds) nozzle beams have been used to generate helium droplets (<N> = 10^4-10^5). The dependence of the beam intensity and the mean droplet size on the source stagnation pressure and temperature are studied via mass…
Besides the use as cold matrix for spectroscopic studies, superfluid helium droplets have served as a cold environment for the synthesis of molecules and clusters. Since vibrational frequencies of molecules in helium droplets exhibit almost…
Controlling the formation and stoichiometric content of desired phases of materials has become a central interest for the study of a variety of fields, notably high temperature superconductivity under extreme pressures. The further…
We show that a 450 fs nonresonant, moderately intense, linearly polarized laser pulse can induce field-free molecular axis alignment of methyliodide molecules dissolved in a helium nanodroplet. Time-resolved measurements reveal rotational…
The motion of electrons in or near solids, liquids and gases can be tracked by forcing their ejection with attosecond x-ray pulses, derived from femtosecond lasers. The momentum of these emitted electrons carries the imprint of the…