Usually polyaniline is made conducting via protonic acid doping e.g. HCl, or via oxidation either chemically or electrochemically. Polyaniline exists in a variety of protonation and oxidation forms. The most important form of polyaninline, green protonated emeraldine is produced by the oxidative polymerization of aniline in aqueous acids. When charges are removed from (or added to) a polymer upon chemical doping, geometric parameters, such as bond length and angles, change and reflected in the FTIR spectrum.

Thank you very much Sir. Is it necessary change in bond length and angle increase intensity ?. It may decrease the intensity also   

Yeh!! its depends on the charge you are adding or subtracting!!!!!