IMAGING BENZENE MOLECULES AND PHENYL RADICALS ON CU(111)

In two sets of experiments built on the work of Brian Bent, we imaged benzene molecules and phenyl radicals on the Cu[111] surface at low co verage and low temperature.(1) The experiments allowed us to see how m obile molecules on surfaces probe the electronic structure of the surf ace. Bare terraces of the Cu[111] surface appear extremely nat in scan ning tunneling microscope images. We are thus able to image the pertur bations to the electronic structure caused by steps, defects, and adso rbates. These perturbations determine the structure and dynamics of th e adsorbates. Benzene forms ordered structures along step edges at eve n very low coverages. Adsorbed phenyl radicals form complex pairs, ali gned so as to be able to couple to form biphenyl at higher temperature . We discuss the chemical consequences of such substrate-mediated inte ractions.