Doped polypyrrole under pressure: Raman investigations

Polyprrole highly doped with tosylate was investigated by Raman spectroscop y using high pressure techniques providing additional information compared to ambient pressure measurements. Changes of band positions and relative in tensities were observed under the view point of the correlation of these ch anges with the nature of the charge carriers in the polymer. The observed r esults are discussed in the framework of the stability of the predominant c harge carriers, bipolarons, in highly doped polypyrrole.