Chirality of p-conjugated polymer films studied by circularly polarized absorption and Raman scattering

We have studied the chirality of two p-conjugated polymers namely achiral polyacetylene and chiral F8BT films, using circular dichroism (CD) spectroscopy and circularly polarized Raman scattering (CP-RS). In our CP-RS studies we have employed four different circularly polarization schemes for the incident and scattered light, respectively. In ‘as prepared’ polyacetylene films we found spot-dependent CD and CP-RS that show polarity reversal that originates from the clockwise and anticlockwise helical arrangements of the fibrils formed by the polymer chain bundling. In contrast, the CD and CP-RS of chiral F8BT film after annealing are unipolar. The difference in CP-RS intensity between co- and cross-polarization was found to be of the order of 1% for both polyacetylene and chiral F8BT.