Photo-Activation of Single Molecules and Assemblies on Au\textbraceleft 111\textbraceright

Understanding electron transfer at the molecular level is critical to the rational design and performance improvement of organic optoelectronics and photovoltaics. The behavior of photoactive molecules depends critically on their local environment and defects present in the surface. Here, we use a custom-built, laser-assisted scanning tunneling microscope to probe the photocurrent of isolated anthracene derivates on Au\textbraceleft 111\textbraceright . The photocurrent originates from charge-transfer transitions of anthracene into an excited state when illuminated by an evanescent field. The influence of the image potential states on terraces and at defects in the gold surface on photo-induced charge transfer will be discussed.