Kong Q, Khakhulin D, Shkrob IA, Lee JH, Zhang X, Kim J, Kim KH, Jo J, Kim J, Kang J, Pham VT, Jennings G, Kurtz C, Spence R, Chen LX, Wulff M, and Ihee H
The photochemical reaction pathways of CHBr 3 in solution were unveiled using two complementary X-ray techniques, time-resolved X-ray solution scattering (TRXSS) and X-ray transient absorption spectroscopy, in a wide temporal range from 100 ps to tens of microseconds. By performing comparative measurements in protic (methanol) and aprotic (methylcyclohexane) solvents, we found that the reaction pathways depend significantly on the solvent properties. In methanol, the major photoproducts are CH 3 OCHBr 2 and HBr generated by rapid solvolysis of iso- CHBr 2 -Br, an isomer of CHBr 3 . In contrast, in methylcyclohexane, iso -CHBr 2 -Br returns to CHBr 3 without solvolysis. In both solvents, the formation of CHBr 2 and Br is a competing reaction channel. From the structural analysis of TRXSS data, we determined the structures of key intermediate species, CH 3 OCHBr 2 and iso -CHBr 2 -Br in methanol and methylcyclohexane, respectively, which are consistent with the structures from density functional theory calculations., (© 2019 Author(s).)