Measurement of the chemical potential of thin helium films

High-precision measurements of third sound velocities in atomically thin $\sp4$He films on Ar, Ne, CO$\sb2$, and H$\sb2$ substrates in the T = OK limit reveal a periodic structure not corresponding to whole layers. We analyze the data in two extreme limits. First, treating the helium film as an incompressible, continuous fluid, the data indicate that the chemical potential has a contribution proportional to $\ell\sp{-6}$, where $\ell$ is a layer coverage, which is modulated at intervals of.62 $\pm$.04 layers, and which weakens the van der Waals potential. Second, if we assume the potential is exactly the van der Waals potential, the data indicate the existence in the film of a damped smectic density wave with a periodicity of.54 $\pm$.04 layers, independent of substrate. The correct description of He films must lie between these extremes. We find the inert layer coverages to be 1 full layer on Ar, Ne, and CO$\sb2$, and.36 layers on H$\sb2$.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Shirron, Peter John

Contributors dc:contributor

• Mochel, J.M.

• Physics, Condensed Matter

Statement dc:rights

• Copyright 1989 Shirron, Peter John

Language dc:language

eng

Identifier

AAI9011023
(UMI)AAI9011023

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/22107