6. Azobenzene as a molecular photocommutator

6.1 Azobenzene monolayer

Surfaces that respond to external stimuli, so-called "smart surfaces", have considerable potential for controlling phenomena such as wetting and de-wetting, (bio)adhesion or catalysis. The preparation of these functional surfaces is difficult and requires the interfacing of delicate organic molecular components with the substrate. In general, metal surfaces are the most widely used, partly because of the well-developed strategies for attaching molecules to these surfaces, and partly because Scanning Tunneling Microscopy (STM), which enables detailed characterization of self-assembled monolayers (SAMs), requires a conductive substrate.

In the case of isomerization induced by the tip of an STM, two mechanisms are at work, depending on...