Pulse radiolysis studies of intermediates derived from p-terphenyl in the oxygenated methyltributylammonium bis[(trifluoromethyl)sulfonyl]imide ionic liquid

Radiation-induced processes in oxygenated ionic liquid (IL) methyltributylammonium bis[(trifluoromethyl)sulfonyl]imide ([MeBu3N][NTf2]) solutions containing p-terphenyl (TP) were investigated by the nanosecond pulse radiolysis with UV-vis detection. The transient absorption spectra generated in these solutions were assigned to radical anions (TP center dot-), radical cations (TP center dot+), and triplet excited states ((TP)-T-3*). Saturation of [MeBu3N][NTf2] solutions with oxygen (O-2) efficiently eliminates solvated electrons (e(solv)(-)); however, it does not decrease significantly the radiation chemical yield of TP center dot-, which are mainly formed in a reaction of TP with presolvated electrons (e(presolv)(-)). On the other hand, the lifetime of TP center dot- decreases significantly due to their reaction with O-2. The TP center dot+ is formed in a reaction of electron-deficient centers of the IL (IL circle plus) with TP. Their radiation chemical yield and lifetime are not affected by the presence of O-2; however, they are decreased by the presence of triethylamine (TEA). The (TP)-T-3* are formed in a reaction of excited states of ionic liquid (IL*) with TP. The presence of O-2 and TEA effectively eliminates (TP)-T-3* in the time domain >1 mu s.