Formation of molecular clusters by percolation of water through p-bromochlorobenzene adlayer on Al2O3(0 0 0 1)

Bilayers of water and p-bromochlorobenzene (BCB) were formed on a surface of Al2O3(0 0 0 1) by vacuum deposition under ultra-high vacuum (UHV) conditions with the BCB adlayer on top. The surface was then heated, allowing water that desorbs at a lower temperature to percolate through the upper BCB layer, leading to the formation of clusters. Percolation and cluster formation caused the water to desorb at temperatures higher than that of multilayer water as detected by temperature programmed desorption (TPD) using a mass spectrometer. The cluster on the surface of Al2O3(0 0 0 1) was tentatively determined to have the composition, (BCB) · H2O.