The influence of hydrogen chloride doping level on the complex refractive indices of anisotropic polyaniline film: Application of a new internal reflection waveguide coupling technique

Nondestructive three-dimensional refractive-index measurements are used for the determination of both crystallinity and orientation in thin polymer fi lms. The prism waveguide coupler is particularly suitable for three-dimensi onal isotropic and anisotropic thin-film studies because of the quantitativ e character of the information obtained and the ease of data acquisition. I t has been limited, however, to measuring the refractive index of optically transparent or weakly absorbing films. This study shows that a modified pr ism waveguide coupler can be used to determine the complex refractive index over a range from transparent to highly absorbing films from the internall y reflected light intensity, Thus, both the refractive index, n, and the ex tinction coefficient, k, can be obtained. This method is used to determine the anisotropic three-dimensional n and k values of spin-coated emeraldine base and hydrogen chloride doped emeraldine salt polyaniline films. (C) 200 1 John Wiley & Sons, Inc.