Abstract/Details

Third sound study of the wetting of rubidium by helium


2000 2000

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Abstract (summary)

Investigation of helium on rubidium, sodium and potassium surfaces followed the cesium studies. My own involvement in wetting experiments was triggered by the results of an experiment conducted by Wyatt and Klier. In their experiment the helium-rubidium system seemed to exhibit nonwet behavior below 300 mK. The very thin film of adsorbed helium on nonwet rubidium seemed to behave like a submonolayer superfluid. From it was born the idea that we could explore superfluidity in the thin film of helium atop rubidium by conducting an experiment which attempts to propagate a tidal-like wave (third sound) along the film.

The basic idea behind the experiment is that third sound can only propagate in films which are superfluid. Therefore, if the thin film of helium on rubidium is superfluid, we can expect to propagate third sound through it. We designed an experiment to examine third sound that propagates across a rubidium substrate. We were able to use the third sound reflection off of the rubidium boundary as a diagnostic to determine when the rubidium was wet (or prewet) by helium and when it was not wet by helium. We produced a rubidium substrate that could be caused to make a transition from being nonwet by helium to being wet by helium. Third sound propagated across the rubidium. We therefore have obtained strong evidence to support the idea that helium in the thin film state on rubidium can behave like a superfluid. We also observed strong evidence that, very close to saturation, the rubidium was always wet by helium to temperatures as low as 150 mK. On a second rubidium surface, the rubidium was always in the wet state, evidence that it is extremely difficult to fabricate rubidium surfaces of reproducible quality.

In this document, we present the results of our third sound experiments on rubidium and explain how we have drawn conclusions about the wetting behavior of helium on rubidium. In addition, a chapter is devoted to some of the low temperature third sound data on glass. (Abstract shortened by UMI.)

Indexing (details)


Subject
Condensation
Classification
0611: Condensation
Identifier / keyword
Pure sciences, Helium, Rubidium, Three-phase fluids, Wetting
Title
Third sound study of the wetting of rubidium by helium
Author
Moreau, Theresa Ann
Number of pages
378
Publication year
2000
Degree date
2000
School code
0118
Source
DAI-B 61/09, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780599957619, 0599957611
Advisor
Hallock, Robert B.
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
9988824
ProQuest document ID
304606312
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304606312
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