Spectroscopic characterization of self-assembled macrocycle monolayers on gold

The use of ultrathin (e.g., 25 Angstrom) gold films on mica as substrates for monolayer deposition enables to obtain UV/vis spectra of monomolecular films containing chromophores. The gold substrate exhibits an array of {111} textured grains, as elucidated from scanning probe and x-ray diffraction measurements. This methodology is applied to the study of the binding of cobalt tetraphenylporphyrin (TPPCo) and cobalt phthalocyanine (CoPc) to 4-mercaptopyridine (4MP) monolayers, self-assembled on ultrathin gold films.