A SCANNING-TUNNELING-MICROSCOPY INVESTIGATION OF 4,4'-DIMETHYLBIANTHRONE MOLECULES ADSORBED ON CU(111)

Well-ordered monolayers of 4,4'-dimethylbianthrone molecules have been grown on a Cu(III) surface in ultra-high vacuum. Scanning tunneling m icroscopy images show the formation of three rotational domains with a molecular arrangement nearly devoid of structural defects. For covera ges below a densely packed monolayer, ordered molecular islands form o n terrace sites away from substrate step edges. Time-lapsed sequences of scanning tunneling microscopy images reveal the coexistence of mole cules in a mobile state together with a fixed two-dimensional molecula r crystal phase. (C) 1997 Elsevier Science B.V.