Growth of corrole films from solution: a nanometer-scale study at the real solid-liquid interface

The self-assembly of corrole molecules dissolved in ethanol and then adsorbed onto an immersed Au(111) surface was investigated by scanning tunneling microscopy (STM) at the solution-solid interface. The physisorption and the subsequent organization of the molecules in multilayers were followed as a function of time at two concentrations, differing by about a factor of 500. In both cases, molecules adsorb flat on the gold surface. For the low concentration, we demonstrate that the first disordered phase is followed, rather abruptly, by a more ordered one, essentially composed of extremely smooth layers of molecules. Even the sharp and winding steps, which mark the layers, describe an evolution toward order. In fact, their rims tend to flatten out, as testified by the decrease in time of their fractal dimension. In the case of high concentration, we have monitored the kinetics of coverage, showing that its evolution for the uppermost layer can be described by Langmuirian kinetics, which provides the adsorption and desorption rate constants, ka = (20.7 ± 1.6) L/(mol s) and kd = (6.5 ± 0.1) × 10-4 s-1.