In Situ Laser Activation of Carbon Fiber Microdisk Electrodes

Carbon fiber microdisk electrodes (11 μm in diameter) were activated in situ via intense laser pulses produced by a small nitrogen laser. The laser beam was focused down to a small spot size to ensure adequate power density. The laser treatment resulted in more Nernstian voltammetry for dopamine, 4-methylcatechol, and 3,4-dihydroxyphenylacetate in several different buffer systems over a range of pHs. The effect of buffer composition and pH on the apparent electrode kinetics observed both before and after laser treatment was studied. An apparent cleaning of the electrode surface by the laser pulses results in more Nernstian voltammetry; however, voltammograms obtained in some buffer systems, particularly those containing citrate, show anomalous effects after laser treatment. A model of the activation process is presented that might explain the observed phenomenon by surface ablation exposing clean, active carbon, followed by adsorption of solution species. This activation procedure is presented as a simple, fairly inexpensive way to obtain consistent, repetitive voltammetry at carbon fiber microdisk electrodes.