Determination of preferential molecular orientation in porphyrin-fullerene dyad zndhd6ee monolayers by the x-ray standing-wave method and x-ray reflectometry

Monolayers of porphyrin-fullerene dyad molecules with zinc atoms incorporated into the por- phyrin ring (ZnDHD6ee) on the surface of aqueous subphase and on Si substrates have been investigated by the X-ray standing-wave method and X-ray reflectometry. The experiments have been performed under lab- oratory conditions and on synchrotron radiation sources (KMC-2 station of BESSY II (Berlin) and Lang- muir station at the National Research Centre "Kurchatov Institute"). Depth distributions of Zn atoms and electron density in the monolayer film are calculated. On the basis of the analysis of these distributions, it is concluded that ZnDHD6ee dyad molecules in monolayers have preferential orientation. The data obtained indicate that the molecules in monolayer film retain their orientation when the monolayer is transferred from a liquid subphase surface onto a solid substrate.