Blocking plasmon-molecule charge transfer using surface ligands

Abstract

We will present the manifestations of plasmon-molecule energy and electron transfer processes as observed surface enhanced Raman spectroscopy (SERS). We observe that in presence of intermediary surface ligands, the electron transfer channel is turned off. On the other hand, the presence of surface ligands facilitates plasmon to molecule energy transfer (plasmon pumped adsorbate intramolecular electronic excitation) by orienting the analyte molecules along the surface field vector as well as by prolonging the excited state lifetime. The adsorbate excitation appears to be followed by singlet to triplet intersystem crossing that leads to singlet oxygen generation that initiates N-demethylation reaction as demonstrated using the reactivity of methylene.