Fig. 2

Raman spectra for pure isomers. a Syn 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (diF-TES ADT) and b anti diF-TES ADT in the 1100–1700cm⁻¹ range. Density functional theory (DFT) calculations are shown in gray. The blue lines indicate vibrational modes associated with the long axis of the acene backbone, which are relatively insensitive to the isomers. The orange lines indicate the short-axis C-C bonds, which are spectrally shifted between the syn and anti isomers