Two Shpolʹskii sites of all-trans-1,8-diphenyloctatetraene in n-tetradecane

Two Shpolʹskii sites of diphenyloctatetraene in n-tetradecane were studied under one- and two-photon excitation. This Shpolʹskii doublet, observable also in the low vibrational frequencies region, corresponds to molecules with broken and unbroken Ag symmetry. A strong vibrational line with relative frequency 1844 cm−1 showed up as a singlet, an effect which needs further studies. Statistical fine structure was used to determine the homogeneous linewidth (110 MHz) and average emission count rate (70 counts/s) for single molecules with unbroken symmetry. The homogeneous width is 1.4–2 times larger than the value estimated for the molecules with distorted symmetry.