Formation and decay of pyrene radical cation and pyrene dimer radical cation in the absence and presence of cyclodextrins during resonant two-photon ionization of pyrene and sodium 1-pyrene sulfonate

摘要: Formation and decay of pyrene radical cation dimer during resonant two-photon ionizations (TPI) (Py) sodium 1-pyrene sulfonate (NaPySA) in the absence presence cyclodextrins were studied with visible near IR transient absorption measurement using 355-nm laser flash photolysis technique. Ionization Py anion (PySA−) occurred within (5 ns) to give (Py˙+) PySA− (Py˙+SA−) having Py˙+ chromophore. Dimerizations Py˙+SA− observed cations (Py2˙+ Py2˙+(SA−)2) based on time-resolved measurements charge resonance (CR) band. The TPI was also examined β- γ-cyclodextrins (βCD γCD, respectively). Py2˙+(SA−)2 cavity two γCDs fully overlapped structure showed CR band around 1700 nm, while βCD partially structures indicated bands 1500 or respectively. On basis formation rates Py2˙+(SA−)2, bimolecular neutralization are inhibited cavities CDs. Selective a is explained by direct PySA−s parallel chromophores γCDs.