High resolution electron energy loss spectroscopy (HREELS) is employed to analyze reversible changes in the geometrical structure of the molecular switch di-methoxy-tetra-tert-butyl-azobenzene (diM-TBA) adsorbed on Au(1 1 1), which are induced by UV-light and thermal activation. While for 1 monolayer (ML) coverage no changes in the vibrational structure due to UV-light exposure at 3.5 eV are observed, illumination of 2 ML of diM-TBA leads to a pronounced modification of the vibrational spectra, which we assign to a t r a n s → c i s isomerization. The reverse process, i.e., the c i s → t r a n s isomerization, can be stimulated by thermal activation. We propose that the photoisomerization is driven by a direct (intramolecular) electronic excitation of the adsorbed diM-TBA molecules in the second ML analogous to diM-TBA in the liquid phase.
- Azobenzene derivative
- Molecular switches
- Reversible isomerization
- Surface vibrational spectroscopy
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry