In this work, the influence of γ radiation on electronic, structural, and vibrational properties of a poly(2,5-thiophene-1,4-dialkoxyphenylene) derivative is studied by optical absorption and photoluminescence. A Gaussian fit of emission spectra within Franck-Condon vertical transitions formalism was carried out in order to understand how vibronic coupling is affected by the dose, because an unexpected luminescence behavior was observed. Aiming to understand the ionizing radiation-matter interaction processes, we employed a molecular modeling procedure, through the use of a semiempirical method (AM1) applied to conjugated oligomers' conformational structure and equilibrium geometries, to clarify the defects induction for the used doses. From AM1 optimized structures, electronic transitions were calculated by ZINDO/S-CI semiempirical method to measure the chain scission degree. Moreover, with the results presented in this work, it is possible to come up with a new physical-chemical route to treat and increase conjugated polymers' efficiency. Finally, we believe that the present paper contributes to the literature about defects on conjugated polymers.
© 2011 American Chemical Society