Polyaniline and Related Systems

The story of ellipsometric studies of polyaniline (PA) shows that increasing sophistication in the technique has led to successively more valuable information from experimental data. In early ellipsometric studies of PA film growth, and subsequent potential cycling, either single A (633 or photoelastic modulation (650-350 ellipsometry (where A and IP only were measured) were 

SIMON J. HIGGINS, PAULA. CHRISTENSEN, AND ANDREW HAMNETT 

A fascinating and important observation is that during oxidation of the polymer, n fell to remarkably low values, particularly at longer X (Table 7.1). Gottesfeld et al. in their work on first pointed out that this is in accord with the 

Optical properties of electroactive polymers as measured ellipsometrically depend greatly on conditions used to grow the film. Greef et al. point out significant optical differences between reduced PA films grown on different materials (for PA, on Pt, n = 1.55-1.58, whereas on Au, n could attain values as high as to 1.7). Explanations in terms of the presence of larger amounts of solvents within reduced films with lower n values (n for aqueous electrolytes is typically ca. 1.34) are not valid. Just as a very low value of n can be traced to a Lorentzian oscillator at 

FIGURE 7.3. Variation of the real (n) and imaginary components of the complex refractive index 

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