Scattering, Trapping, and Ionization of HCl at the Surface of Liquid Glycerol

Abstract

A model for the interactions between HCl and liquid glycerol, based on the Empirical Valence Bond (EVB) approach, is developed and used to investigate by molecular dynamics computer simulations the early events following the collision of an HCl molecule with the glycerol surface. The calculated trapping probability at 2.4 and 22 kcal/mol collision energies and the fractional energy loss of scattered HCl molecules agree well with experiments. The potential of mean force for HCl in the bulk and at the glycerol surface exhibits a low barrier to the formation of the contact ion pair, suggesting the possibility of proton transfer at the interface. Trapped HCl molecules undergo rapid relaxation and solvation and begin to form contact ion pairs on the picosecond time scale, which is consistent with the low barrier to the formation of the ion pair derived from the equilibrium potential of mean force calculations.