Reversible switching of tetra-tert-butyl-azobenzene on a Au(1 1 1) surface induced by light and thermal activation

Two-photon photoemission spectroscopy is employed to analyze reversible changes in the electronic structure of the molecular switch tetra-tert-butyl-azobenzene (TBA) adsorbed on Au(1 1 1), which are induced by UV-light and thermal activation. Cycles of illumination and annealing steps confirm the reversibility of the switching process, which we assign to a trans/cis-isomerization of TBA molecules in direct contact with the Au(1 1 1) surface. Pronounced changes in the photoelectron spectra due to UV-light exposure allow to calculate an effective cross section of σeff ≈ 8 × 10−22 cm−2 at 4.14 eV and σeff ≈ 4 × 10−21 cm−2 at 4.4 eV, respectively, for the trans- to cis-isomerization.