Following a Photoinduced Reconstructive Phase Transformation and its Influence on the Crystal Integrity: Powder Diffraction and Theoretical Study

In the course of solid‐state photoreactions, a single crystal (SC) of the reactant can be transformed into an SC of the product or it can lose crystallinity and become amorphous. In‐between these two scenarios exist the reconstructive phase transformations, where upon irradiation, the reactant SC becomes a powder or an SC with increased mosaicity. We present a detailed description of reconstructive photodimerization, where the structural changes are directly correlated with the disintegration process. The kinetics of the reaction is explained by two kinetic regimes, forming an autocatalytic autoinhibition photoreaction set with high quantum yield. In addition, the photoreaction pathways were studied theoretically. Changing phases: In the course of solid‐state photoreactions, the single crystal of a reactant can be transformed into a single crystal of the product or it can become amorphous. Between these scenarios exist the reconstructive phase transformations, where the single crystal becomes a powder. A detailed description of the latter is given.