Tip Induced Isomerization of Azobenzene Derivatives*

The adsorption and trans-cis isomerization of azobenzyl thiols (ABT) on the Ag tip and Ag(111) surface are studied using density functional theory (DFT) calculations. The trans states is the most stable adsorption configuration on both Ag tip and Ag(111) surface. However, their switching behaviours are distinct. The trans-cis ismoerization of ABT is suppressed on Ag(111) surface, while the swithcing energy barrier is dramatically decreased by the Ag tip. The driving mechanisms are investigated by charge transfers to reveal the physical inisights and to provide guidance for the realization of molecular-based swithcing devices. Further more, we have calculated the Raman spectral to directily compare with the experiment.