New Techniques in UV-visible Reflection Measurements

The time resolution of this optical probe is remarkable, making it possible to monitor adsorption dynamics at the interface not readily accessible by other techniques. The same group has recently reported the time-resolved reflectance spectroscopy of a polycrystaUine Pt microelectrode using a laser source and a beam-splitter/microscope objective arrangement [96]. 

By the use of collimated laser light divided into double beams, one can measure the reflectance at two spots on one single facet, as shown schematically in Fig. 2.30 [97]. 

The position and distance of the two spots are variable. This approach has merit for the following reasons One can see whether the process of interest is of mean-field type or nucleation-growth. In the former case, the reflection signals at the two spots as the response to a single potential step should be a identical function of time. Additionally, one can see the two-dimensional uniformity of the kinetics or one can estimate the rate of the surface diffusion process. 

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