Helium is considered an almost ideal tagging atom for cold messenger spectroscopy experiments. Although helium is bound very weakly to the ionic molecule of interest, helium tags can lead to shifts and broadenings that we recorded near 963.5 nm in the electronic excitation spectrum of C60+ solvated with up to 100 helium atoms. Dedicated quantum calculations indicate that the inhomogeneous broad...

Neutron inelastic scattering studies of the elementary excitations in con ned super uid He are reviewed. Both recent work on helium in porous silica glass (aerogel, Vycor, etc.) and earlier work on helium lms on graphite surfaces are discussed. The global picture emerging from these studies is that the three-dimensional excitations are essentially the same as in bulk helium. The characteristic ...

The infrared spectroscopy of molecules, complexes, and molecular aggregates dissolved in superfluid helium clusters, commonly called HElium NanoDroplet Isolation (HENDI) spectroscopy, is an established, powerful experimental technique for extracting high resolution ro-vibrational spectra at ultra-low temperatures. Realistic quantum simulations of such systems, in particular in cases where the s...

Early measurements of the specific heat of liquid helium confined in all three spatial dimensions suggest a coupling of individual regions of superfluid via connecting channels. Preliminary measurements have been made to investigate this apparent coupling. Although more data need to be collected before anything conclusive can be said, the available data support the idea that behavior of helium ...

This paper introduces a nonlinear Schrr odinger model for superruid that captures the process of mutual friction between the superruid and normal uid components of helium II. Superruid vortices are identiied as topological defects in the solution of this equation. A matched asymptotic analysis of Neu 7] is adapted to derive an asymptotic dynamics for the vortices in the case they are widely sep...

We present evolutionary models of helium accreting carbon-oxygen white dwarfs in which we include the effects of the spin-up of the accreting star induced by angular momentum accretion, rotationally induced chemical mixing and rotational energy dissipation. Initial masses of 0.6 M⊙ and 0.8 M⊙ and constant accretion rates of a few times 10−8M⊙/yr of helium rich matter have been considered, which...

Helium at low temperatures has unique quantum properties such as superfluidity, which causes it to behave differently from a classical fluid. Despite our deep understanding of quantum mechanics, there are many open questions concerning the properties of quantum fluids in nanoscale systems. Herein, the quantum behavior of helium transportation through one-dimensional nanopores was evaluated by m...

Suicide by helium inhalation inside a plastic bag has recently been publicized by right-to-die proponents in "how to" print and videotape materials. This article reports a suicide performed according to this new and highly lethal technique, which is also a potentially undetectable cause of death. Toxicology information could not determine helium inhalation, and drug screening did not reveal dat...

Excitation spectra up to the ionization threshold are reported for barium atoms located on the surface of helium nanodroplets. For states with low principal quantum number, the resonances are substantially broadened and shifted towards higher energy with respect to the gas phase. This has been attributed to the repulsive interaction of the excited atom with the helium at the Franck-Condon regio...

Helium has a unique phase diagram and below 25 bar it does not form a solid even at the lowest temperatures. Electrostriction leads to the formation of a solid layer of helium around charged impurities at much lower pressures in liquid and superfluid helium. These so-called 'Atkins snowballs' have been investigated for several simple ions. Here we form HenC60+ complexes with n exceeding 100 via...