Stark effect, electrochemical interface

Because of the short lifetime of ions in gaseous atmospheres, even at low pressure, gas-phase IR measurements are limited to adsorption of neutral molecules. Electrochemical applications of the IR method offer the interesting possibility of providing data on the adsorption properties of charged particles (Secs. 8 and 9). In the electrochemical environment the applied potential allows ionic adsorbates to be studied under energetically controllable conditions. Otherwise the electrochemical double layer offers exceptional conditions to investigate the Stark effect on vibrational transitions by setting tunable electric fields of the order of 10 V cm at the interface. This phenomenon will be discussed in Sec. 10. 

In electrochemical systems the energetics of the interface can be controlled very elegantly by changing the electrode potential. In the case of CO adsorption, mechanisms such as backbonding should be very sensitive to potential change, i.e., to the electronic density of the surface. Furthermore, the strong electric field in the inner double layer can produce a band shift known as the Stark effect, as discussed in Sec. 10 in more in detail. 

The Stark effect requires the application of electric fields of the order of 10 Vcm or higher. The electrochemical interface, where molecules and ions are subjected to fields in the order of 10 Vcm S seems to be the ideal place to study this phenomenon. 

Lambert, D.K. (1996) Vibrational Stark effect of adsorbates at electrochemical interfaces. Electrochimica Acta, 41, 623-630. 

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