Stochastic resonance in electron transfer oscillations of extended viologen

Selective generation of only odd harmonics and the absence of even harmonics were never described for electrochemical oscillators though this phenomenon is known in special fields of physics and in biological systems. The heterogeneous electron transfer to the extended viologen with four repetitive viologen units yields electrochemical current oscillations. Small perturbation of the applied voltage by only a few millivolts sine wave results in current oscillations, which selectively enhance only the odd harmonic higher frequencies. The effect is explained in terms of the theory of stochastic resonance occurring in driven oscillating reactions. The described interplay of heterogeneous and homogeneous coupled electron transfers complies with the behavior of a nonlinear potential-symmetric system. © 2014 American Chemical Society.