Transient absorption and fluorescence measurements of free radical cation and radical ion pair during pulse radiolysis of 1,3,5-trimethoxybenzene in chlorinated solvents

Transient absorption and laser-induced fluorescence measurements of 1,3,5-trimethoxybenzene radical cation (TMB⋅+) during the pulse radiolysis in chlorinated solvents at room temperature have revealed the formation of an ion pair [TMB⋅+ Cl−] both through fast and slow processes, electron transfer from TMB to chlorine atom and collision between TMB⋅+ and Cl−, respectively. Fluorescence quantum yield (Φf) measurement has indicated that excited TMB⋅+ (TMB⋅+*) in the ion pair undergoes electron transfer quenching by Cl− with a rate constant of 3.0×1011 s−1 and fluoresces weakly (Φf=3.1×10−5) as compared to free TMB⋅+* (Φf=1.1×10−3).