High-resolution electron energy loss spectroscopy (HREELS) is employed to analyze reversible changes in the geometrical structure of the molecular switch tetra-tert-butylazobenzene (TBA) adsorbed on Au(111), which are induced by UV-light and thermal activation. In the submonolayer regime, TBA adsorbs in the planar trans configuration. UV-light exposure at 3.5 eV leads to pronounced changes in the vibrational structure of the TBA molecules in direct contact with the Au(111) surface, which we assign to a trans to cis isomerization. The reverse process, that is, the cis to trans isomerization, can be stimulated by thermal activation. An intensity decrease of vibrational modes as a function of photon dose allows calculation of an effective cross section of σeff ≈ 2 × 10-21 cm2 for the trans to cis isomerization.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films