Spectroelectrochemistry specular reflectance

Figure 28. Configurations for spectroelectrochemistry. A) optically transparent electrode B) optically transparent thin-layer electrode (OTTLE) C) Internal reflection spectroscopy, and D) specular reflectance spectroscopy.

Figure 44. Electrode systems for spectroelectrochemistry (a) optically transparent electrode, (b) electrode for internal reflection spectroscopy, and (c) electrode for specular reflectance spectroscopy.

In the reflection mode, typically specular reflectance is measured on the electrode surface. It is anticipated that the variation of the surface structure (e.g., surface adsorption, phase transitions, etc.) will result in appreciable changes in the reflectivity properties. One can thus correlate the structural characterislics gleaned from spectroscopic measurements with electrochanical results. Figure 2.15 shows a cell assembly for internal reflection spectroelectrochemistry. Several spectroscopic techniques have been used, such as infrared, surface plasmon resonance, and X-ray based techniques (reflectivity, standing wave, etc.). Figure 2.16 depicts a cell setup for (A) infrared spectroelectrochemistry (IR-SEC) and (B) surface X-ray diffraction. 

Reflectance accessories are available on modern UV-vis spectrometers and many are available which allow for variation of the incident angle for separation of specular reflectance and diffuse reflectance. Reflectance UV-vis has found applicahon in spectroelectrochemistry of thin films, polymer modified electrodes, and surface adsorbates such as self-assembled mono- and multilayers. A number of cell designs have been apphed and these are generally designed to fit into commercial reflectance attachments. A thin film reflectance cell is shown in Figure 14.8 (34). The electrode was fabricated by anodizahon of a thin layer... 

When Desilvestro and Pons used in situ IR reflection spectroelectrochemistry to observe the reduction of C02 to oxalate at Pt electrodes in acetonitrile [83], two different forms of oxalate were observed. Similarly, Aylmer-Kelly et al. studied C02 reduction in acetonitrile and propylene carbonate at Pb electrodes [84], by using modulated specular electroreflectance spectroscopy. Subsequently, two radical intermediates were observed which they determined to be the C02 radical anion, C02, and the product of the radical anion and C02, the (C02)2 adduct (see Equations 11.9 and 11.10). Vassiliev et al. also studied the reduction of C02 in... 

---