DETERMINATION OF THE VISIBLE SPECTRA OF ELECTRODE-REACTION PRODUCTS IN STRONGLY ABSORBING MEDIA BY DIFFUSION-CONTROLLED CHRONOABSORPTOMETRY

Chronoabsorptometry under diffusion-controlled conditions has been app lied to determination of the difference in molar absorptivity between electrode reaction products and reactants. The technique allows comple te determination of the ultraviolet-visible spectra of reaction produc ts that are stable on the time scale of a few hundred milliseconds. Th e technique was implemented with a reflectance cell that employs quart z light pipes to minimize optical absorbance of the bulk solution with out obstructing the current path between counter and working electrode s. The spectrum of one-electron oxidized chloro-(5,10,15,20-tetrapheny lporphinato)Fe(III) is determined with the new technique and compared with that obtained by conventional thin-layer spectroelectrochemistry.