Lawrence Berkeley National Laboratory

We have studied the effect of mechanical energy transfer from the tip of an Atomic Force Microscope on the dynamics of self-assembly of monolayer films of octadecylamine on mica. The formation of the self-assembled film proceeds in two successive stages, the first being a fast adsorption from solution that follows a Langmuir isotherm. The second is a slower process of island growth by aggregation of the molecules dispersed on the surface. We found that the dynamics of aggregation can be altered substantially by the addition of mechanical energy into the system through controlled tip-surface interactions. This leads to either the creation of pinholes in existing islands as a consequence of vacancy concentration, and to the assembly of residual molecules into more compact islands.