Direct ionization-driven radical cation formation observation methods in solution

Understanding early-stage reaction dynamics of ionizing radiation-induced reaction, it is essential to make direct observation of kinetics of the excess electron and its parent radical cation species. The primary process of the excess electron is relatively well examined according to the advances of pulse radiolysis technique. On the other hand, the counterpart radical cations have been examined with less benefit of advances of the time-resolution of the pulse radiolysis. The observation of solute radical cations was achieved in halogenated hydrocarbons like dichloromethane or 1,2-dichloroethane. The solute radical cations were generated with hole transfer reactions between the solvent radical cation and the solute in those solvents. After this process, the solute radical cations can be observed with the aid of conversion of the excess electron to the less reactive halide anion like Cl–. The hole transfer reaction's diffusion process limits the apparent time-resolution in the pulse radiolysis measurement to study ultra-fast reaction dynamics of the radical cations in solution. Therefore, a new approach to radical cation generation is needed