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J. Pavelec, P. Ryan, J. Balajka, M. Schmid, U. Diebold:
"Surface tension measurement of pure water in vacuum";
Poster: DPG-Frühjahrstagung (DPG Spring Meeting) of the Surface Science Division, SurfaceScience21, virtual; 01.03.2021.

Very little is known about the surface tension of pure liquids in contact with their pure gaseous phases, i.e. without the presence of other gases or liquid phase contaminants. This is surprising given that contaminants are known to greatly affect surface tension values [1].

Recently we have developed a method to dose liquid water onto pristine surfaces in UHV using a small cryostat [2,3]. We combine this approach with the pedant drop method [4] to measure the surface tension of ultra-clean liquids in contact with their pure gaseous phases. The upgraded version of the small cryostat, replaces the syringe typically used in the pendant-drop method. The ultra-clean liquid is condensed onto a small cryostat placed in a vacuum chamber. A pendant drop is formed, photograph and analyzed allowing the surface tension of the liquid to be directly determined.

The design of the apparatus will be discussed and preliminary measurements of ultra-clean water will be presented.

[1] Uematsu, Bonthuis, Netz, Current Opinion in El., Vol. 13, (2019)

[2] Balajka, Pavelec, Komora, Schmid, and Diebold, Review of Scientific Instruments 89, (2018)

[3] Balajka, Hines, DeBenedetti, Komora, Pavelec, M Schmid, U Diebold, Science, 361, (2018)

[4] Berry, Neeson, Dagastine, Chan, Tabor, J. Coll. Interface Sci. 454, 226, (2015)