Experimentally observed orientation of C60F18 molecules on the nickel single crystal (100) surface

The angular dependence of near edge X-ray absorption fine structure (NEXAFS) spectra has been obtained in the vicinity of carbon and fluorine 1s absorption edges in a monolayer film of polar fullerene fluoride (C₆₀F₁₈) molecules on a Ni(100) substrate. The fine structure of the spectra has been identified according to experimental data via calculations based on the density functional theory, and the angular dependence of the spectra has been explained. The orientations of structural molecular fragments are determined from the angular dependence of the NEXAFS spectra. It is demonstrated that the electric dipole moment of a C₆₀F₁₈ molecule is oriented along the normal to the substrate surface with an accuracy of 5°.