Transmission-Mode SPELs

The interpretation of reflection mode data is a bit less straightforward than the transmission mode SPELs above, since one has to contend with slight differences... 

The simplest spectroelectrochemical measurement which yields information on electrochromic properties of CPs is the UV-Vis-NIR spectroelectrochemical curve, an in-situ or sometimes ex-situ measurement of the transmission-mode UV-Vis-NIR spectrum of the CP at various applied potentials. Such a measurement, which we shall hereinafter abbreviate as a SPEL curve (or just SPEL), is depicted in Fig. 3-1 this figure is a re-representation of the optical spectra of poly(pyrrole) (P(Py)) discussed in Chapter 2, with an abscissa in terms of wavelength, and represents a particularly well-behaved CP system. To recap again here, the single, prominent valence conduction (tt tt ) band transition in the pristine polymer (at ca. 388 nm) is accompanied by three additional polaron based transitions at low doping level (ca. 590 nm, 885 nm, 1,771 nm), which finally evolve into two bipolaron based bands (ca. 459 nm, 1,240 nm). 

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