In-Situ Growth Studies of Organic Monolayer and Multilayer Structures. P. Fenter, Princeton Materials Institute, Princeton University, Princeton NJ 08544

We have used in-situ, real-time x-ray diffraction measurements to probe the growth of organic film systems, including "self-assembled monolayers" (SAMs) and multilayer films consisting of supra-molecular aggregates. We find that the molecular-level SAM growth process (via vapor phase growth, in vacuo) of the widely studied decanethiol/Au(111) system exhibits a number of unexpected and novel features, including the presence of multiple self-assembly mechanisms as a function of growth conditions (due to a number of distinct adsorption energetics), and a complex coverage-temperature phase diagram which has an important impact upon the evolution of order within the monolayer, resulting in distinct "high" and "low" temperature growth regimes. We have also studied the growth of "co-assembled" films (via a solution- phase growth process on mica surfaces) which consist of a lattice of supra- molecular surfactant micelles which co-assembles with an inorganic phase (in this case silica) resulting in an organic/inorganic nano-composite material. Our results show that the co-assembly process results in high quality films, and reveal a number of surpises. For example, we find that the "epitaxy" of the micelles results in preferred orientation of the micellar lattice, and the growth proceeds in a highly non-linear fashion. These results demonstrate that in-situ real-time studies of growth are essential to understand the molecular-level growth processes associated with complex "soft matter" systems.

This work was performed in collaboration with A. Eberhardt, L. Zhou, F. Schreiber, T.Y.B. Leung, D. Lavritch, P. Schwartz, S. Wetterer, M. Bedzyk, L. Berman, I. Aksay, P. Eisenberger, G. Scoles.