Infrared Surface Polariton Spectroscopy

In Section 3.3 we have considered surface polaritons which are surface electromagnetic excitations propagating along a surface or an interface. Their amplitude has a maximum at the boundary between two contacting media. This feature leads to a strong influence of the surface/interface properties on the SP characteristics. SPs excited in the IR spectral region are, therefore, sensitive optical probes of vibrations in both the substrate crystal and the overlayer. On 

The dispersion law which dictates the conditions of SP excitation is determined by the optical constants of the bordering media. On the other hand, the presence of a film or an adsorbed layer at the interface modifies the dispersion relation and thus allows one to extract information on optical properties of an overlayer. These two approaches are used as the basis of various experimental techniques. 

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In Section 4.3 we have considered surface polariton spectroscopy in the infrared region. As distinct from that case, SPs in the optical spectral range exist mainly on metal surfaces, i.e., as surface plasmon polaritons (SPP). The SPP dispersion curve extends from the far-infrared up to the far-ultraviolet region and thus it can be excited at any frequency in this range. This allows one to use SPPs as an optical probe of various overlayers on metal surfaces and in-... 

Instrumentation. In order to employ local enhancement of infrared absorption by surface plasmon polaritons that cause locally enhanced surface electromagnetic fields, a suitable optical arrangement is needed [295]. Surface enhanced infrared absorption spectroscopy can also be observed in the transmission mode [285, 296]. However, since no application of this approach in spectroelectrochemistry has been reported so far, it is not discussed further. 

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