Spatial correlation of photoisomerization of functionalized azobenzene molecules on a surface

Photoactive azobenzene molecules have great potential for nanoscale opto-mechanical applications. We report a scanning tunneling microscopy (STM) study of the time-dependence of photo-switching tetra-\emph{tert}-butyl-azobenzene (TTB-AB) molecules on Au(111). ``Switched'' molecule concentrations were measured as a function of exposure time to various incident light wavelengths until stationary concentrations were reached. We examined the spatial correlations of the photo-switching rates. Scanning tunneling spectroscopy was used to reveal the possible dependence of switching dynamics on the electronic structure of the islands. Implications for organic photoactive devices will be discussed.