Self-assembled structure of alkyloxy substituted benzoic acid methyl ester on HOPG:An STM study

Self-assembled structures of 3,4,5-tris-dodecy- loxy benzoic acid methyl ester (E12), 3,4,5-tris-tetradecy- loxy-benzoic acid methyl ester (E14) and their mixture (E12/E14) have been studied on HOPG by scanning tunnel- ing microscopy (STM). Dimer-like patterns induced by di- pole-dipole interaction are observed in E12 and E14 monolayers. The molecules form close-packed rows and in- terdigitate with the alkyl chains in adjacent molecules. The structural differences are proposed to be from the different length of substituted alkyl chains. Owing to similar adsorp- tion energy, phase separation is observed in the E12 and E14 mixed adlayer with different domains.