[Laser photolysis study on photochemical reactions in mixed solutions of [bmim][PF6] and acetonitrile]

Laser flash photolysis study was carried out for the first time in the binary mixture of room-temperature ionic liquid (RTIL) and traditional organic solvent. Photochemical properties of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6] and its binary mixed solutions with MeCN were investigated by laser photolysis technique at an excitation wavelength of 355 nm, using anthraquinone (AQ) as a probe molecule. It was indicated that [bmim] [PF6] itself participates in the reaction with 3AQ*. Moreover, along with the change in the ratio of RTIL to organic solvent, the decay reaction rate constant of 3AQ* changes regularly and a critical point was observed at chiRTIL = 0.06. Before the critical point, the decay rate constant increases rapidly with increasing chiRTIL; however, it decreases obviously with increasing chiRTIL after the critical point. The kinetic data are given, and the possible reaction mechanisms in mixed solutions are also speculated.