The interfacial structures of biphenyl (BP), benzoic acid (BA), and 4-biphenylcarboxylic acid (BPCA) on
a Au colloid monolayer surface were investigated using surface-enhanced Raman scattering (SERS). The
absence of the C−H stretching vibrational mode in the SERS spectrum of BP indicated that the two
benzene rings of BP were coplanar on the Au colloid surface, while their twisted structure was suggested
in the bulk state. The downward frequency shift of the carboxylate stretching vibrational mode of BA
implied the direct chemical adsorption of the carboxylate group onto the Au surface with a flat orientation.
In BPCA, an absence of the C−H stretching vibrational mode and the red shift of the carboxylate stretching
vibrational mode were observed. This fact strongly indicated that both the two benzene rings and the
carboxylate group were adsorbed on the Au surface with flat orientation via their π-systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.