Microscopic insights into nucleation in a sulfuric acid—water vapor mixturebased on molecular dynamics simulation

摘要

We conducted a molecular dynamics simulation of the binary nucleation in the vapor mixtureconsisting of water and a small amount of sulfuric acid and investigated the microscopic process inrelation to the structure of the hydrate (binary cluster composed of sulfuric acid and water). It wasobserved that the nucleation rate increased with the concentration of sulfuric acid. It was found thatthe formation of the hydrate is stable as long as its size is small enough, and the hydrate growth bycoagulation played a major part in the enhanced nucleation. The rate of coagulation became largerby the uptake of more sulfuric acid in the hydrate, while it was suppressed with increasing thehydration number. We found that such features came from the structure of the small hydrate whichwas a multishell structure composed of an inner shell of sulfuric acid and diffused outer shell ofwater.