ORDERING OF DIDODECYLBENZENE ON GRAPHITE - A COMBINED SFM STM STUDY

We report on scanning force microscopy (SFM) images resolving the lamella structure of didodecylbenzene (DDB) physisorbed at the interface between its organic solution and the basal plane of highly oriented pyrolytic graphite (HOPG), as well as on large-scale molecularly resolved scanning tunneling microscopy (STM) images of the same system. SFM imaging on length scales of 10 nm and more reveal the onset of 3D island growth, with a morphology changing with time. High-resolution SFM images of monolayers could be obtained by using metal-coated cantilever tips biased at + 4 V during SFM operation. Large-scale STM images taken over up to 2-mu-m allow the boundaries of entire domains to be observed, with single domains extending over more than 0.5-mu-m. While the large domains are stable with time, smaller domains are observed to spontaneously reorient. Finally, the domain structure at monatomic graphite steps is investigated.