Figure 3.

Single molecule and single particle spectroelectrochemistry in NEAs. (A) E-ZMWs shown schematically (i) and in a cross-sectional SEM image (ii). E-ZMWs exhibiting fluorescence emission within the nanopore array, scale bar 2 μm (iii). The redox behavior of individual flavin mononucleotide (FMN), a voltage-sensitive dye is fluorescent in the oxidized state, but dark in the reduced state. An unusual intermediate state is tentatively assigned to a stabilized semiquinone species (iv). (B) Schematic illustration of a dual-ring E-ZMW operating in either non-GC (i) or GC mode (ii), along with cross-sectional image (iii). The light is strongly trapped within the bottom ring region of the nanopore, as indicated by the simulation (iv). The electrochemical signals from the anode and cathode are strongly correlated with each other and with the fluorescence signals from the interrogated sub-array. Transients are assigned to population fluctuations arising from capturing or losing individual FMN molecules (v). (C) Schematic illustration of families of collision dynamics represent either Type A: aggregation-induced collisions, (i) or Type B: multiple single particle collisions, (ii), of AgNPs in the confined environment. Top-view SEM image of a single ring NEA (iii) and simulated particle collisions inside nanopores (iv). Raman spectra of bis-MSB tagged nanoparticles are evident in SERS spectra displaying two distinct types of temporal dynamics (v). Panel A is adapted with permission, ref 30. Copyright 2015 The Royal Society of Chemistry. Panel B is adapted with permission, ref 31. Copyright 2017 The Royal Society of Chemistry. Panel C is adapted with permission, ref 37. Copyright 2019 American Chemical Society.