Spectroscopic Characterization of the Bonding, Orientation, and Coverage of Copper Tetraazaphthalocyanine Monolayer Films on SiO<INF>2</INF> Surfaces

Self-assembled monolayer films of a metallotetraazaphthalocyanine were prepared using two different reaction conditions. The films were characterized by ellipsometry, AFM, electronic absorption spectroscopy, semiempirical MO calculations, core-level XPS, and projection of a calculated structure of the chromophore onto a surface to obtain its silhouette area for comparison with surface concentration from absorption spectroscopy. A denser packing of the chromophores is found in the SAM film prepared with bromonaphthalene at 250 &#176;C as compared with the film from the more polar solvent DMF at 120 &#176;C. Data is consistent with an almost vertical orientation of the chromophores in the former film. A different number of bonds connecting the chromophore with the coupling molecule is suggested as an explanation to differences in the absorption bands for the two films.