In situ and interrupted-growth studies of the self-assembly of octadecyltrichlorosilane monolayers

We have examined the self-assembly process of octadecyltrichlorosilane on s ilicon using x-ray reflectivity. By comparing the commonly used "interrupte d-growth" characterization technique with results obtained in situ, we have determined that quenching the growth and then rinsing and drying the sampl e introduces free area into the film, presumably by removal of non-cross-li nked (physisorbed) molecules. Reintroduction of a quenched and rinsed film to solvent does not restore the thickness of the film to its previous value . We have also performed in situ growth studies over a range of concentrati ons. For all concentrations, we observe growth of islands of vertical molec ules; The growth follows Langmuir kinetics, except at short times for low c oncentration solutions. PACS number(s): 68.45.-v, 82.65.My, 81.15.Lm.