Dissociation of HCl into Ions on Wet Hydroxylated (0001) α‑Quartz

The acidification of surfaces in the natural and built environments is important to atmospheric science because the process can enhance chemistry at surfaces and increase the release of highly reactive products into the gas phase. We present the results of an ab initio molecular dynamics study using density functional theory of HCl ionic dissociation on the hydroxylated (0001) α-quartz surface. We observed that at temperatures in the range of 250–300 K, HCl ionizes rapidly on a surface wetted with a water monolayer. It seems that ionization is enhanced by lattice mismatch between the silica and water layer. The first proton transfer to a neighboring water molecule initiates proton migration within the water adlayer via the Grotthuss mechanism. Spectroscopic signatures for the ionization are calculated and are in fair agreement with experiment