Experimental observation of the layering and wetting of multilayer liquid helium-4 films on graphite

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5264148

Kumar, S

The multilayer adsorption of liquid /sup 4/He on graphite was studied by using third sound, a substrate-induced surface wave in a superfluid film, to probe the /sup 4/He film-vapor interface. The third-sound velocity decreases with increasing film thickness and can be used to monitor the film growth. Graphite, forms of which have large areas of atomic uniformity, is an ideal substrate for the study of film growth and layering. An annular resonator made out of graphite fibers was used for the experiments. Such a resonator avoids problems such as capillary condensation present in earlier resonance experiments with graphite foam and vapor sound interference present in time-of-flight experiments with highly oriented pyrolitic graphite (HOPG). Measurements of film growth were made between temperatures of 0.35 and 1.25 K. The third-sound resonance frequency, which is proportional to the third-sound velocity, was used to follow the film growth. Simultaneous measurements of the third-sound velocity on glass provide an independent measure of the film thickness. Results obtained show continuous film growth up to at least 25 to 30 layers on graphite. Oscillations of the third-sound velocity for low film coverages shown evidence of layering of the film.

• Research Organization: Pennsylvania State Univ., University Park (USA)
• OSTI ID: 5264148
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARBON
ELEMENTAL MINERALS
ELEMENTS
EVEN-EVEN NUCLEI
FILMS
GRAPHITE
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LAYERS
LIGHT NUCLEI
MINERALS
NONMETALS
NUCLEI
STABLE ISOTOPES
SUBSTRATES
SUPERFLUIDITY
THIRD SOUND
WETTABILITY