IN-SITU RAMAN SPECTROELECTROCHEMICAL STUDIES OF POLY(3,3'-DIBUTOXY-2,2'-BITHIOPHENE)

Raman ''in situ'' spectroelectrochemical studies have been carried out in order to elucidate the electrochemical doping of poly(3,3'-dibutoxy-2,2'-bithiophene). Raman spectra registered at different potentials strongly depend on the position of the excitation line with respect to the electronic spectrum of the polymer. In particular, blue (458 nn) and red (676 nm) excitation lines are very insensitive toward the oxidative doping of the polymer and independently of the electrode potential always give spectra characteristic of the unoxidized segments of the chain. To the contrary, the infrared excitation line (1064 nm) allows for detailed monitoring of the oxidative doping. The changes in the spectra occurring upon increasing potential of the electrode are consistent with the doping-induced transformation to the quinoid structure. The proposed assignments of the observed Raman bands have been confirmed by the vibrational analysis involving the calculation of the force field and frequencies via Fourier's dynamical matrix.