Electronic properties of the conducting form of polyaniline from electroabsorption measurements

The polaron band at ∼1.4 eV of d,l-camphorsulfonic acid-doped polyaniline ((±)-HCSA-PANI) in a poly(methyl methacrylate) (PMMA) matrix was studied using electroabsorption (Stark-effect) spectroscopy at 298 K. A very small change in dipole moment on excitation (|Δμ|) in the order of 1.4±0.2 D was measured as well as an average change in polarizability (Δα) of only −1.3±0.4 Å3. The electroabsorption signal of (±)-HCSA-PANI in this region showed evidence for heterogeneity in the absorption band.