C-60-PROPYLAMINE ADDUCT MONOLAYERS AT THE AIR-WATER-INTERFACE

X-ray reflectivity measurements and surface-pressure isotherms of spre ad films of the fullerene-propylamine adduct (C-60-[NH2(CH2)(2)CH3](12 )) indicate that despite the lack of definite amphiphilic character, t his material forms a homogeneous monomolecular layer on water surfaces . X-ray reflectivity data, taken at various lateral pressures, were fi tted to a model structure defined in terms of the dimensions of an ave rage cell and its chemical compositions. At T = 18 degrees C, the late ral pressure versus area per molecule is indicative of a structural ph ase transition presumably from one closely-packed phase to another, as the total thickness of the film is consistent with a single layer of 15 Angstrom thickness. At pressures above 30 mN/m the film consists of an inhomogeneous bilayer, consistent with a layer thickness of 26 Ang strom.