| Abstract
| - The interaction of CsCl with solid water, deposited on tungsten at 130 K, was investigated. Metastable impactelectron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy [UPS(He I)] were applied to studythe emission from the ionization of Cl(3p) and Cs(5p) and 1b1, 3a1, and 1b2 of molecular water. Below acritical stoichiometry of about CsCl·6H2O the UPS spectra are quite similar to those for co-deposition ofwater and CsCl on tungsten, also studied here, and from chlorides solvated in liquid water inasmuch as therelative positions and intensities of the water and salt features are concerned. Very little emission fromCl(3p) and Cs(5p) is observed with MIES. We propose that CsCl dissociates, and the resulting ions becomesolvated in solid water. For supercritical stoichiometries Cs and Cl appear at the solid water surface andbecome accessible by MIES. CsCl-induced destruction of the water network takes place at the surface, andwater molecules interact mainly with Cs and Cl, rather than with other water molecules. When subcriticalfilms are heated above 135 K, the water-induced part of the spectrum changes its shape and becomes moregas phase like. Beyond 160 K no water can be detected with MIES. Above this temperature only Cs and Clare found on the surface and desorb around 450 K. We have also studied water adsorption at 130 K on CsClfilms. CsCl becomes solvated and migrates into the water overlayer.
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