Towards Determining Kinetics of Annihilation Electrogenerated Chemiluminescence by Concentration-Dependent Luminescent Intensity

Abstract

In ion-annihilation electrochemiluminescence (ECL), luminophore ions are generated by oxidation as well as reduction at electrodes surfaces, and subsequently recombine into an electronically excited state, which emits light. The intensity of the emitted light is often limited by the kinetic rate of recombination of the luminophore ion species. Recombination or annihilation rates are high ranging up to approximately 10 10 M −1 s −1 and can be difficult to determine using scanning electrochemical microscopy or high-frequency oscillations of an electrode potential. Here, we propose determining annihilation kinetics by measuring the relative change of the emitted light intensity as a function of luminophore concentration. Using finite element simulations of annihilation ECL in a geometry of two closely spaced electrodes biased at constant potentials, we show that, with increasing concentrations, luminescence intensity crosses over from a quadratic dependence on concentration to a linear regime-depending on the rate of annihilation. Our numerical results are applicable to scanning electrochemical microscopy as well as nanofluidic electrochemical devices to determine fast ion-annihilation kinetics.

Electrochemiluminescence reaction pathways in nanofluidic devices

“…Light intensity was recorded through the bottom electrode and device substrate correlation of both current-time traces indicates an annihilation reaction (reactions 1-4). The current increases as the annihilation route is much more efficient in shuttling electrons across the inter-electrode distance compared to redox cycling [20,26].…”

Data-Driven Modeling of Smartphone-Based Electrochemiluminescence Sensor Data Using Artificial Intelligence

“…For this, it is necessary to obtain the experimental measurements of the main state variables (e.g., concentration of luminophore and co-reactant) over the course of ECL reaction at regular time intervals, which is not a straightforward task [6]. The proper choice of the reaction rates and their corresponding kinetic parameters to propose a reliable mechanistic model is the subject of considerable discussion in recent literature [6,7,15,16]. In other approaches, the so-called calibration curve, i.e., a regression equation, can be useful to infer the concentration of Ru(bpy) 2+ 3 if it is correlated with a key feature of the system such as the maximum value of the ECL intensity.…”

Determination of organophosphate flame retardant tris(2‐chloroethyl)phosphine based on the luminol–H2O2 chemiluminescence system

“…[22] CL detection methods are some of the most sensitive and selective detection techniques in analytical chemistry. [23][24][25][26][27] CL has the following advantages. First, compared with other optical reactions, there is no need to excite a light source, which gives rise to a lower background signal, an extremely low detection limit, and a broad dynamic range.…”