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^•−), radical cations (TP^•+), and triplet excited states (³TP*). Saturation of [MeBu₃N][NTf₂] solutions with oxygen (O₂) efficiently eliminates solvated electrons (e_solv⁻); however, it does not decrease significantly the radiation chemical yield of TP^•−, which are mainly formed in a reaction of TP with presolvated electrons (e_presolv⁻). On the other hand, the lifetime of TP^•− decreases significantly due to their reaction with O₂. The TP^•+ is formed in a reaction of electron-deficient centers of the IL (IL^⊕) with TP. Their radiation chemical yield and lifetime are not affected by the presence of O₂; however, they are decreased by the presence of triethylamine (TEA). The ³TP* are formed in a reaction of excited states of ionic liquid (IL*) with TP. The presence of O₂ and TEA effectively eliminates ³TP* in the time domain >1 μs.