Synchronised photoreversion of spirooxazine ring opening in thin crystals to uncover ultrafast dynamics

Reversibility is an important issue that prevents ultrafast studies of chemical reactions in solid state due to product accumulation. Here we present an approach that makes use of spectrally-selected, post-excitation, ultrashort laser pulses to minimise photoproduct build-up, i.e. recover before destroy. We demonstrate that this method enabled us to probe the ultrafast dynamics of the ring opening reaction of spironaphthooxazine thin crystals by means of transient absorption spectroscopy. By extension, this approach should be amenable to other photochromic systems and use with structural probes.