Infrared and Raman microspectroscopy have been used to follow the photodimerisation reactions of single crystals, the α-and β-forms of trans-cinnamic acid. This approach allows the starting materials and products—α-truxillic acid that has Ci symmetry and β-truxinic acid, which has Cs symmetry—to be identified. It also allows the topotactic nature of the reaction to be confirmed. Attempts to produce the poorly-defined unreactive γ-form of trans- ...
