Phase transitions of adsorbed atoms on the surface of a carbon nanotube.

Phase transitions of adsorbed atoms and molecules on two-dimensional substrates are well explored, but similar transitions in the one-dimensional limit have been more difficult to study experimentally. Suspended carbon nanotubes can act as nanoscale resonators with remarkable electromechanical properties and the ability to detect adsorption at the level of single atoms. We used single-walled carbon nanotube resonators to study the phase behavior of adsorbed argon and krypton atoms as well as their coupling to the substrate electrons.

Classical rotational inertia of solid 4He.

The observation of reduced rotational inertia in a cell containing solid 4He has been interpreted as evidence for superfluidity of the solid. We propose an alternative explanation: slippage of the solid, due to grain boundary premelting between the solid and dense adsorbed layers at the container wall. We calculate the range of film thickness, and determine the viscosity that will account for the missing rotational inertia.

Frost heave in argon.

The freezing of argon in silica powder is observed to generate bands of pure solid argon in the same manner as in the phenomenon of ice lens formation in the freezing of moist ground. A first principles dynamical theory describes the mechanism of lens formation by the thermomolecular pressure-driven flow of interfacially melted films at the lens-solid boundary.

Thermomolecular pressure in surface melting: motivation for frost heave.

A thermomolecular pressure is associated with surface melting, and it can drive mass flow along an interface under a lateral temperature gradient. The pressure is a universal thermodynamic function in the limit of thick films. It may be responsible for frost heave in frozen ground.