Upon investigation of the II-III transition mechanism via Raman spectroscopy, we observed something quite unexpected: we see the marked weakening of the core stretching peak ν(C=C) ECC,Q at 1387 cm -1 , while 2 new peaks appear at higher wavenumbers, 1442 and 1497 cm -1 (Figure ). This indicated a modification to the conjugated core itself. We initially suspected this may be a degradation of the molecule at such high temperatures. However, the temperature at which the peaks appeared were highly correlated with the II-III transition and, moreover, this peak formation was found to be reversible (Figure ). Along with this, we also observed a change in the intensity ratio between the peaks located at 1025 and 1063 cm -1 , previously assigned to the trans (ν(C-C) T ) and gauche (ν(C-C) G ) isomers, respectively. Based on these observations, we hypothesize a transformation from a quinoidal structure to aromatic structure accompanied by decreased order of the alkyl side chains; such quinoidal to aromatic transitions have been observed in similar systems .