Surface plasmon study of electrochemically prepared polymers: Polyazulene

The work reported here shows that by using a modified gold working electrode, the surface plasmon technique can successfully be used to obtain information on the optical constants and the film thickness of electropolymerized films. Polyazulene films deposited at three different surface charge densities are investigated in the oxidized and corresponding reduced forms. Our result shows that the refractive index, and hence the dielectric constant at 632 nm, is complex, the imaginary part being larger for the oxidized form compared to that for the corresponding reduced form. Thickness determination shows that its relationship with the amount of charge is qualitatively similar to that reported for polypyrrole. The film thickness measurement reveals a shrinkage in going from the oxidized to the reduced form as the counter anions are removed. Our study, therefore, shows that the surface plasmon technique can be used to probe ionic processes.