IN-SITU SCANNING-TUNNELING-MICROSCOPY OF BENZENE, NAPHTHALENE, AND ANTHRACENE ADSORBED ON CU(111) IN SOLUTION

In situ scanning tunneling microscopy (STM) was used to probe the adla yer structures of benzene, naphthalene, and anthracene on a well-defin ed Cu(lll) electrode surface in aqueous HClO4 solution. These molecule s were found to form highly ordered adlayers on a clean Cu(lll) surfac e with a flat-lying orientation. The molecular orientation and packing arrangement were also determined. The ordered benzene adlayer was obs erved to form a (3 x 3) structure with a characteristic triangular sha pe for each benzene molecule. The naphthalene adlayer was observed wit h a (4 x 4) symmetry. The naphthalene molecules were preferentially al igned with their long Ct axes along the atom rows of the Cu(lll) subst rate. A long range ordered structure was also found for the anthracene adlayer. Straight molecular chains formed along the atomic rows of Cu (lll) with a side-by-side configuration.