Derivative linear sweep and derivative cyclic voltabsorptometry of the long-path-length spectroelectrochemical cell: The single reversible electrode reaction

Abstract

This paper presents the theory of derivative linear sweep and derivative cyclic voltabsorptometry (DLSVA and DCVA) of the long-path-length spectroelectrochemical (SEC) cell for the single reversible electrode reaction. Assuming that only the oxidized species (Ox) absorbs at the measurement wavelength initially, the first- and second-derivative optical responses for two cases, i.e. thin layer diffusion for Ox + ne− ⇄ Red (reduced species) or Red ⇄ Ox + ne− and semi-infinite diffusion for Ox + ne− ⇄ Red or Red ⇄ Ox + ne−, have been discussed via digital simulation, etc. All types of theoretical behaviour have been compared with that of the optically-transparent electrode (OTE). The results show that DLSVA and DCVA of the long-path-length SEC cell are more sensitive (by several decades or more) than those of the OTE. The theoretical results are verified experimentally by the well-characterized reversible electrochemical system Fe(CN) 6 3−/Fe(CN) 4 3− in 0.5 M HNO 3 + 0.5 M glycine buffer.