Scanning tunnelling microscopy structural information from

There has also been interest in studying adsorbed layers on the electrode surfaces by spectrometric methods, either with the electrode immersed in the solution (e.g., by ellip-sometry, surface enhanced Raman spectroscopy, scanning tunneling microscopy) or after removal emersion) of the electrode from solution. These methods are useful, since they can supply information about the structure of the adsorbed layer. They are discussed briefly in Chapter 17. 

Since the early days of modern surface science, the main goal in the electrochemical community has been to find correlations between the microscopic structures formed by surface atoms and adsorbates and the macroscopic kinetic rates of a particular electrochemical reaction. The establishment of such relationships, previously only developed for catalysts under ultrahigh vacuum (UHV) conditions, has been broadened to embrace electrochemical interfaces. In early work, determination of the surface structures in an electrochemical environment was derived from ex-situ UHV analysis of emersed surfaces. Although such ex-situ tactics remain important, the relationship between the structure of the interface in the electrolyte and that observed in UHV was always problematic and had to be carefully examined on a case-by-case basis. The application of in-situ surface-sensitive probes, most notably synchrotron-based surface X-ray scattering (SXS) [1-6] and scanning tunneling microscopy (STM) [7, 8], has overcome this emersion gap and provided information on potential-dependent surface structures at a level of sophistication that is on a par with (or even in advance of) that obtained for surfaces in UHV. 

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