Can p,p′-Dimercaptoazobisbenzene Be Produced from p-Aminothiophenol by Surface Photochemistry Reaction in the Junctions of a Ag Nanoparticle−Molecule−Ag (or Au) Film?

In this study, we attempt to experimentally address the question of whether p,p′-dimercaptoazobisbenzene (DMAB) can be produced from p-aminothiophenol (PATP) by surface photochemistry reaction in the junctions of a Ag nanoparticle−molecule−Ag (or Au) film. First, utilizing surface-enhanced Raman scattering (SERS) spectra, we provide experimental and theoretical evidence that DMAB can be produced from PATP by surface photochemistry reaction in the junctions of a Ag nanoparticle−molecule−Ag film. Second, we investigate the SERS spectra utilizing both experimental and theoretical approaches, ultimately revealing that DMAB cannot be produced from PATP in the junctions of a Ag nanoparticle−molecule−Au film. The electromagnetic enhancements are estimated with three-dimensional finite-difference time domain methods, which are about 9 × 105 times in the junctions of Ag nanoparticle−PATP−Ag/Au films.