ORDER AND DISORDER IN C-60 LANGMUIR-BLODGETT-FILMS - DIRECT IMAGING BY SCANNING TUNNELING MICROSCOPY AND HIGH-RESOLUTION TRANSMISSION ELECTRON-MICROSCOPY

C60 forms very rigid insoluble films ("monolayers") at the air-water interface (collapse pressure PI(c) = 62.5 mN/m). The "area per molecule' A0 = 21.6 angstrom2 (at zero pressure) and A(c) = 11.5 angstrom2 (at PI(c)) are too small for a single C60 molecule and suggest 4-7.5 C60 molecules piled on top of each other, per "monolayer". C60 forms Langmuir-Blodgett (LB) films on glass and HOPG and Langmuir-Schaefer (LS) films on a Cu grid. The ellipsometric LB film thickness is about 2 molecules per "monolayer". The STM (LB) and HRTEM (LS) images show that the C60 films have 2-dimensional and 3-dimensional crystalline regions. The STM image shows a slightly distorted {013} projection of an face-centered cubic (fcc) pattern of roundish, atomically unresolved peaks, with a cell constant of 14.2 angstrom. The HRTEM micrographs and a selected-area electron diffraction pattern show that, at optimum crystallinity, the C60 molecules pack in an fcc pattern with a cell constant of 14.20 +/- 0.05 angstrom. No hexagonal close-packed structures were found.