ELECTROREFLECTANCE OF WELL-DEFINED PT SURFACES

A method has been devised to carry out UV/vis electroreflectance studies on electrodes making a meniscus contact with the electrolyte. In this way the electrochemical state of the surface can be monitored at the same time as the electroreflectance is studied. Experiments have been carried out on Pt single crystals oriented to expose the low index plans (111), (100) and (110). The region from the adsorption of hydrogen to the early stages of the adsorption of oxygen species has been studied in the wavelength range 365 nm to 630 nm. The characteristics of the reflectance change in the hydrogen region differ from those in the oxygen region and confirm that the so-called 'anomalous' region may be attributed to hydrogen adsorption.