Fundamentals of real-time surface plasmon resonance-electrogenerated chemiluminescence

We report the integration of surface plasmon resonance (SPR), cyclic voltammetry and electrochemiluminescence (ECL) responses to survey the interfacial adsorption and energy transfer processes involved in ECL on a plasmonic substrate. It was observed that a Tween® 80/tripropylamine nonionic layer formed on the gold electrode of the SPR sensor, while enhancing the ECL emission process, affects the electron transfer process to the luminophore, Ru(bpy)32+, which in turn has an impact on the plasmon resonance. Concomitantly, the surface plasmon modulated the ECL intensity, which decreased by about 40%, due to an interaction between the excited state of Ru(bpy)32+ and the plasmon. This occurred only when the plasmon was excited, proving that the optically excited surface plasmon leads to lesser plasmon mediated luminescence and that the plasmon interacts with the excited state of Ru(bpy)32+ within a very thin layer. Hence, this work lays the foundation for the combination of classical SPR and ECL and investigates the interfacial processes occurring during ECL.