surface science

Well-ordered monolayers of 4,4'-dimethylbianthrone molecules have been grown on a Cu ( l l 1) surface in ultra-high vacuum. Scanning tunneling microscopy images how the formation of three rotational domains with a molecular arrangement early devoid of structural defects. For coverages below a densely packed monolayer, ordered molecular islands form on terrace sites away from substrate step edges. Time-lapsed sequences of scanning tunneling microscopy images reveal the coexistence of molecules in a mobile state together with a fixed two-dimensional molecular crystal phase. © 1997 Elsevier Science B.V