Apparatus for dosing liquid water in ultrahigh vacuum

J. Balajka, J. Pavelec, M. Komora, M. Schmid, U. Diebold

Institut für Angewandte Physik, TU Wien, 1040 Wien, Austria
Central European Institute of Technology, Brno 61200, and Institute of Physical Engineering, Brno University of Technology, Brno 61669, Czech Republic

Rev. Sci. Instrum. 89 (2018) 083906

The structure of the solid-liquid interface often defines the function and performance of materials in applications. To study this interface at the atomic scale, we extended an ultrahigh vacuum (UHV) surface-science chamber with an apparatus that allows bringing a surface in contact with ultrapure liquid water without exposure to air. In this process, a sample, typically a single crystal prepared and characterized in UHV, is transferred into a separate, small chamber. This chamber already contains a volume of ultrapure water ice. The ice is at cryogenic temperature, which reduces its vapor pressure to the UHV range. Upon warming, the ice melts and forms a liquid droplet, which is deposited on the sample. In test experiments, a rutile TiO2(110) single crystal exposed to liquid water showed unprecedented surface purity, as established by X-ray photoelectron spectroscopy and scanning tunneling microscopy. These results enabled us to separate the effect of pure water from the effect of low-level impurities present in the air. Other possible uses of the setup are discussed.

Corresponding author: Ulrike Diebold (diebold at iap_tuwien_ac_at).

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