文摘
Previous studies have shown that the gas-phase fragmentation of the retinal chromophore after S0–S1 photoexcitation results in a prominent fragment of mass 248 which cannot be explained by the cleavage of any single bond along the polyene chain. It was therefore theorized that the fragmentation mechanism involves a series of isomerizations and cyclization processes, and two mechanisms for these processes were suggested. Here we used isotope labeling MS–MS to provide conclusive support for the fragmentation mechanism suggested by Coughlan et al. (J. Phys. Chem. Lett. 2014, 5, 3195).