Scanning Electrochemical Microscopy-Attenuated Total Reflection Spectroscopy

6 Scanning Electrochemical Microscopy-Attenuated Total Reflection Spectroscopy 

A novel combination of SECM with mid-infrared (IR) (3-25 pm wavelength region) spectroscopy was reported by Kranz et al. [158,159]. Here, the SECM substrate is the flat top of a hemispherical ZnSe attenuated total reflection (ATR) single bounce crystal. IR radiation is directed through the crystal and focused onto a small spot at the ATR crystal-solution interface. The locally created evanescent field penetrates a few microns into solution and the radiation reflected at the interface (internally reflected) is directed toward a photodetector. Hence, IR-adsorbing molecules present in the close vicinity of the interface can be spectroscopically probed, that is, an evanescent field adsorption spectrnm is acquired. 

So far, only insulating ATR-SECM substrates (ATR crystals) have been used. However, ATR-SECM conducting substrates could, in principle, be fabricated by coating ATR crystals with mid-IR transparent conducting thin films (such as diamond-like films). Combining ATR-SECM with AFM for simultaneous in situ studies on topography, IR spectroscopy, and electrochemical processes is also contemplated [159]. 

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Wang L, Kowalik J, Mizaikoff B, Kranz C (2010) Combining scanning electrochemical microscopy with infrared attenuated total reflection spectroscopy for in situ studies of electrochemically induced processes. Anal Chem 82 3139-3145... 

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