| Abstract
| - Surface segregation of iodide, but not of fluoride or cesium ions, is observed by a combination of metastableimpact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS(HeI)) of amorphoussolid water exposed to CsI or CsF vapor. The same surface ionic behavior is also derived from moleculardynamics (MD) simulations of the corresponding aqueous salt solutions. The MIES results show the propensityof iodide, but not fluoride, for the surface of the amorphous solid water film, providing thus strong evidencefor the suggested presence of heavier halides (iodide, bromide, and to a lesser extent chloride) at the topmostlayer of aqueous surfaces. In contrast, no appreciable surface segregation of ions is observed in methanol,neither in the experiment nor in the simulation. Furthermore, the present results indicate that, as far as thethermodynamic aspects of solvation of alkali halides are concerned, amorphous solid water and methanolsurfaces behave similarly as surfaces of the corresponding liquids.
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