Highly ordered p-xylene adlayer formed on Rh(111) in HF solution: In situ STM and ex situ LEED

Structure of the adlayer of p-xylene on Rh(111) in HF solution was investig ated by the complementary use of in situ scanning tunneling microscopy (STM ) and ex situ low-energy electron diffraction (LEED). In situ STM images re vealed that p-xylene molecules lie flat on the Rh(lll) surface, forming a h ighly ordered adlayer with a c(2 root3 x 4)rect structure. High-resolution imaging revealed not only the packing arrangement but also the internal str ucture of each molecule. Two methyl functional groups at the para position of benzene were clearly discerned. The adlayer structure obtained by LEED w as consistent with that determined by in situ STM.