Hot electron-induced electrogenerated luminescence of Tl(I) at disposable oxide-covered aluminum electrodes

Cathodic pulse polarisation of oxide-covered aluminum electrodes in TI(I) s olutions induce strong T1(I)-specific electrogenerated luminescence (EL). I t is mainly regarded as electrochemiluminescence, induced by one-electron o xidation of cathodically produced thallium atoms in the close vicinity of t he electrode surface; but solid state electroluminescence is also produced, especially, with thicker oxide films. Depending on the EL system applied, the oxidant in response of the excitation event is either a cathodically pr oduced hydroxyl or sulfate radical, or an F+-centre of the thin oxide film, and the source of short-lived thallium atom colloids is a reduction of T1( I) ions by tunnel-emitted hot electrons and/or cathodically generated hydra ted electrons. The present method allows the detection of TI(I) ions below nanomolar concentration level and provides linear log-log calibration graph s spanning several orders of magnitude of concentration of T1(I). (C) 1999 Elsevier Science B.V. All rights reserved.