Studies on polyaniline by terahertz time-domain spectroscopy

Abstract

An important challenge in the field of terahertz (THz) spectroscopy is to be at par with existing characterization techniques in the other part of the electromagnetic spectrum. In this study, THz time-domain spectroscopy (TDS) was used to characterize polyaniline (PAni). The THz conductivity of PAni emeraldine salts (ES) was measured using a THz-TDS set-up. The PAni samples were prepared with varying doping time, annealing time and compression pressure. It was found out that the THz conductivity follows the ω⁵ -dependence which is the Mott-Davis form. The parameter S, which ranges from 0 to unity, is inversely proportional to doping state. This is consistent with the decrease of S with longer doping time. Also, there is an increase of S with longer annealing time. Lastly, the compression pressure varies directly with the THz conductivity that suggests a contribution of interparticle conduction.