Dissociation of water on the surface of organic salts studied by X-ray photoelectron spectroscopy.

Water dissociation has important implications for numerous chemical processes. Although extensively studied on metals and to some extent on inorganic salts, this phenomenon has not yet been shown to occur on organic surfaces. Herein, the ability of two crystalline organic hydrochloride salts to induce water dissociation at their surface was demonstrated. Using a modified X-ray photoelectron spectroscopy setup, the oxygen lacking crystalline organic salts were exposed to high water vapor pressures within an environment sealed from ambient air. Thus, the O(1s) peak resulting from exposure to water vapor at room temperature could be unambiguously assigned to dissociated water, a phenomenon previously unreported with organic material. Both powder and single crystal samples were investigated, to determine the effect of defects on the extent of dissociation. Dissociation was shown to be dependent on the level of defects present at the surface. The presence of highly reactive dissociated water on organic surfaces has important implications for the solid state chemical stability of these substances.