Hot electron-induced electrogenerated chemiluminescence of 1-aminonaphthalene-4-sulphonate at oxide-covered aluminium electrodes in aqueous solution

Electrogenerated chemiluminescence of 1-aminonaphthalene-4-sulphonate (ANS) provides a sensitive means for the detection of the ANS in aqueous solution when oxide-covered aluminium electrodes are used as tunnel emission electrodes and cathodic pulse polarisation is used for the excitation of the luminophore. During the pulse polarisation of insulating oxide film-coated aluminium cathodes, hot electrons are tunnel emitted from the aluminium to the aqueous electrolyte solution by direct field-assisted tunnelling (in the case of oxide films of thickness 2–6nm) or by Fowler–Nordheim (FN) tunnelling in the cases of thicker oxide films. As a result of direct tunnel emission of these energetic electrons, the generation of hydrated electrons (eaq−) becomes possible. These electrochemically generated, extremely strong reductants (dry hot or hydrated electrons) make the efficient excitation of various types of luminophores at thin insulating film-covered electrodes possible and provide a means for sensitive immunoassays and DNA-probing assays when these luminophores are used as label molecules.