화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.120, No.25, 6336-6344, 1998
The role of substrate identity in determining monolayer motional relaxation dynamics
We report on the lifetime-and motional dynamics of Zirconium Phosphonate (ZP) monolayers containing oligothiophene chromophores in a range of concentrations. Monolayers were formed on fused silica substrates and on a 15 Angstrom oxide layer formed on crystalline Si(100) substrates. For both interfaces, the fluorescence lifetime behavior of the chromophores is identical and does not depend on chromophore concentration within the monolayer. Transient anisotropy measurements reveal that, for both substrates, the chromophores are oriented at similar to 35 degrees with-respect to the surface normal. For monolayers formed on silica, there is no evidence for chromophore motion, while motion is seen for monolayers formed on silicon. Despite the substantial similarity between the two families of monolayers, the surface roughness of the primed silicon substrate allows for greater motional freedom of the chromophores in the monolayers. We discuss these findings in the-context of the differences in substrate surface roughness and domain sizes as measured by atomic force microscopy (AFM).