Surface Plasmon Resonance-Induced Charge Transfer in Ag/Mercaptobenzoic Acid/Polyaniline Sandwich Structures

Tunable surface plasmon resonance (SPR) of silver (Ag) films fabricated via magnetron sputtering technology was achieved. The experimental findings demonstrated that the thickness of the Ag film gradually increased with increasing sputtering time, resulting in a red shift of the SPR peak. To investigate the charge transfer (CT) induced by SPR in a metal/probe molecule/organic semiconductor system, a composite system composed of Ag nanoparticles, mercaptobenzoic acid (MBA), and polyaniline (PANI) was prepared by a layered assembly method. Notably, the surface-enhanced Raman scattering (SERS) intensity of the Ag/MBA/PANI system increased significantly with the introduction of PANI. The contribution of CT was evaluated by using the CT degree of the Ag/MBA/PANI system. On the basis of these results, the CT direction was confirmed by 2D correlation spectroscopy, revealing that the Ag/MBA/PANI system had good stability and excellent SERS performance. This development opens up novel possibilities and perspectives for the fabrication of SERS-active substrates.