Adsorption of Organic Molecules on Large Water Clusters

Abstract

The sticking efficiencies for a range of organic molecules (methanol, propan-2-ol, acetone, acetaldehyde, formic acid, benzene, trimethylamine, and ethene) onto large water clusters, containing several hundred water molecules, have been determined using a supersonic molecular beam expansion to generate the water clusters and the pickup technique to deposit the organic molecule onto the cluster. It is believed that the organic molecule remains adsorbed onto the surface of the cluster and is not incorporated into the bulk of the cluster. The relative sticking coefficients are found to correlate with the magnitudes of the interaction energy for the organic molecule and water. It is suggested that the higher sticking efficiencies (e.g., for formic acid and acetaldehyde) may result from the molecules forming more than one hydrogen bond to the water cluster.