Reversible switching in self-assembled monolayers of azobenzene thiolates on Au (111) probed by threshold photoemission

► Photoelectron spectroscopy of liquid phase prepared SAMs of azobenzene derivative. ► Photo-induced reversible switching in densely packed SAM is monitored. ► Maximum density of switched molecules in SAM is derived from photoemission data. ► Switching reaction only enabled at defects sites within the molecular layer.