The considerable activity in the area of organic thin films, involving very thin polymeric films and molecular monolayers and multilayers, led to the formation of a panel, sponsored by the Materials Sciences Division of the Department of Energy, to review this field. Its purpose was to better understand the relevant scientific topics and to suggest suitable areas of research. In particular, a number of potential applications were identified, which require further scientific advances for them to see fruition. These include nonlinear and active optical devices, chemical, biochemical, and physical sensors, protective layers (e.g., for passivation), patternable materials both for resists and for mass information storage, surface modification (e.g., wetting and electrochemical electrode properties), and synthetic biomacromolecules. Studies of these films have the added advantage that they could lead to a better scientific understanding of such subjects as the relationships between the microstructure of ordered molecular arrays and their collective properties, the tailoring of interfaces and surfaces, especially when used to model multibody interactions, and the physical and chemical reactions of films involving phase transitions and intraand interfilm transport. The areas that appear to require the most attention include the application of new characterization techniques, such as the scanning tunneling microscope, the improvement of mechanical and thermal stability, the identification and characterization of physical and chemical defects, and the effects of internal ordering on macroscopic properties. It is further recommended that strong interdisciplinary efforts be mounted to address and solve these problems.

No abstract

Carbon K-shell NEXAFS (near edge x-ray absorption fine structure) spectra of oriented hydrocarbon chains in Langmuir–Blodgett (LB) monolayers were measured and used to study the orientation of these molecules. The LB monolayers were assembled from arachidic acid or cadmium or calcium arachidate on the oxidized Si(111) surface. The observed NEXAFS resonances are assigned to transitions to excited states which are localized on individual CH2 groups or C–C bonds. From a detailed analysis using curve-fitting techniques of the angular dependence of the various spectral peaks, the hydrocarbon chains of the cadmium arachidate monolayer is estimated to lie within 15° of the surface normal, the hydrocarbon chains of the calcium arachidate monolayer is estimated to be tilted by 33±5° from the surface normal, while the arachidic acid monolayer is not ordered at all. The determined chain orientations are discussed in terms of a microscopic model involving lateral interactions between the zig–zag hydrocarbon chains.

No abstract