Specular reflection, electrode-solution

Ito et a/.18 supported the above reaction pathways for various cathode materials, such as In, Sn, Cd, and Pb, from the similarity in Tafel slopes. Hori and Suzuki46 verified the above mechanism in various aqueous solutions on Hg. Russell et al.19 also agreed with the above mechanism. Adsorbed CO J anion radical was found as an intermediate at a Pb electrode using modulated specular reflectance spectroscopy.47 This intermediate underwent rapid chemical reaction in an aqueous solution the rate constant for protonation was found to be 5.5 M-1 s-1, and the coverage of the intermediate was estimated to be very low (0.02). 

Electrode surface derivatization with Id and 4a. In a typical experiment, Au or Pt electrodes of the appropriate size were soaked in a 0.1 mM hexane solution of Id for 24 h. Cyclic voltammetry in CH2C12/Bu4NPF6 solution indicated monolayer coverage (4-8 x 10 10) of Id as did specular reflectance FTIR spectroscopy. The Id treated electrodes were then soaked in a 0.1 M hexane solution of 4a for 15 min. Cyclic voltammetry in CH2C12/Bu4NPF6 indicated that the monolayer formed in this manner consisted of approximately 1 1 ld 4a. 

Exposure of a Id and a 4a treated electrode to CO. An electrode treated with Id and 4a in the aforementioned manner was placed in a 50 mL 3-neck flask containing 30 mL of 0.1 M CH2C12 solution of Bu4NPF6. CO was then bubbled into the solution for 10 min and a cyclic voltammogram was subsequently recorded. The wave assigned to Id had shifted +120 mV relative to the 4a wave. Similarly, when a lxl cm2 Au electrode treated with Id and 4a was placed in a vial and purged with CO for 10 min, specular reflectance IR indicated surface conversion of Id to 2d. 

The mechanistic details of the anodic alkylbenzene oxidation have been under intense investigation. In the early stages of this research the major issue was the order of the electron and proton transfer steps leading to the benzyl cations and whether the second electron-transfer reaction takes place at the anode (ECE) or in solution (DISP) see Eq. (7). By the application of a combination of voltammetry and specular reflectance spectroscopy [173,192-195], it has been possible to monitor the electrode surface by UV-visible spectroscopy during electrolysis at controlled potential or to monitor the absorption at a predetermined value as a function of potential. In this way absorption spectra, which were attributed to the radical cation, XIII, the benzyl radical, XIV, formed by deprotonation, Eq. (60), the benzyl cation XV, and the N-benzylnitrilium ions, XVI, have been recorded in MeCN. 

Specular Reflection of Light at an Electrode-Solution Interface... 

Instrumentation. The electrochemical cells described in the preceding section can be used. A cell design with a significantly reduced radiation absorption of the electrolyte solution film as used for specular X-ray reflectivity measurements (see description below Fig. 6.10) can also be used. Electrode potentials are selected based on standard electrochemical experiments (e.g. cyclic voltammetry) with respect to well-defined changes of the electrode-solution interface (e.g. potential steps between potentials of complete desorption and maximum adsorption). Control of the potentiostat and the X-ray diffractometer as well as data acquisition, storage and manipulation are done with a suitably programmed computer. 

Posdorfer J, Olbrich-Stock M, Schindler RN (1994) Electrochim Acta 39 2005 Posdorfer J, Olbrich-Stock M, Schindler RN (1994) J Electroanal Chem 368 173 Hansen WN (1973) Internal reflection spectroscopy in electrochemistry. In Muller RH (ed) Advances in electrochemistry tmd electrochemical engineering, vol 9. John Wiley, New York McIntyre IDE (1973) Specular reflection spectroscopy of the electrode-solution interphase. In Muller RH (ed) Advances in electrochemistry and electrochemical engineering, vol 9. John WUey, New York... 

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