Uptake of Hydrogen Bonding Molecules by Benzene Nanoparticles

The uptake of molecules on nanometer-size clusters of polyaromatic hydrocarbons (PAHs) is important for the condensation of water on PAH aerosols in the atmosphere and for ice mantle growth on nanoparticles in the interstellar medium. We generate benzene dusters Bz(N) of mean size (N) over bar approximate to 300 (radius (R) over bar approximate to 2.2 angstrom) as a model system for the PAH nanoparticles. Using molecular beams and mass spectrometry detection, we investigate the uptake of water, methanol, and ethanol by these dusters. All picked up molecules are highly mobile on Bz(N) and generate clusters within <3 ms. The relative uptakes for the different investigated molecules can be directly compared and quantified. Water molecules exhibit the lowest relative pickup probability that is similar to 30% lower than those for methanol and ethanol, which are approximately the same.