UV-induced desorption-retrapping cycle of electrochemically adsorbed CO onPt(111) surface

UV irradiation (266 nm) from a nanosecond and/or a femtosecond laser-induce d reconstruction of CO adsorbed layer on Pt(111) electrode. The current pea k shape in the cyclic voltammogram (CV) for the electrochemical oxidation o f the adsorbed CO was varied by the irradiation, which did not leave any ch ange in the CV response on the adsorption free Pt(111) surface. Although th e current peak shape in the CV was changed, the total charge for the CO oxi dation remained constant. The green light irradiation (532 fim) from the la sers did not induce any change in the CV. These findings suggested that the UV induced CO desorption and re-trapping cycles were sustained on the elec trode surface, which passed through electronic excited states at the surfac e.