Polymorphism and Phonon Dynamics of α‐Quaterthiophene

Two 4T: Low‐frequency micro‐Raman spectroscopy coupled with lattice dynamics calculations is an invaluable tool for investigating polymorphism in organic semiconductors. The Raman spectra of the low‐temperature (LT) and high‐temperature (HT) polymorphs of α‐quaterthiophene (4T) are presented and interpreted (see picture). Raman mapping is applied to investigate the phase purity. magnified image Low‐frequency (10–150 cm −1 ) Raman spectra of the low‐temperature (LT) and high‐temperature (HT) polymorphs of the organic semiconductor α‐quaterthiophene at 300 and 10 K are reported. Polarized spectra, assisted by quasi‐harmonic lattice dynamics (QHLD) calculations, allow characterization of the lattice phonon dynamics and identification of the two phases spectroscopically. The experimental data can be explained by taking into account the coupling between intermolecular (lattice) and low‐frequency intramolecular modes. Finally, Raman mapping is used to investigate the phase purity.