PNNL

Abstract

The transition path sampling technique was used to determine trajectories connecting the interface and bulk for the transfer of a hydroxyl radical from the air-water interface to the water bulk. The trajectories were used to calculate the rate of transfer for the process. In addition, transition state and Grote-Hynes theories were used to calculate the rate of transfer. It was found that transition state theory significantly overestimated the rate of transfer, while the Grote-Hynes theory estimated a transmission coefficient that was fairly close to that from transition path sampling. Analysis of transition states found that a majority of them were not at the free energy barrier from the potential of mean force, but shifted towards the vapor phase. This work was supported by the Office of Basic Energy Sciences of the Department of Energy, in part by the Chemical Sciences program and in part by the Engineering and Geosciences Division. The Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.