Formation of excited singlet toluene in the radiolysis of alkane containing toluene in the solid phase at 77 K

Abstract

When alkane containing a small amount of toluene is irradiated by γ-ray or X-ray in the solid state at 77 K, luminescence from excited toluene is observed. The formation of the excited toluene is not due to direct excitation of toluene by γ-ray or Čerenkov light, but to the rapid energy transfer from the irradiated alkane to toluene. The intensity of luminescence from the excited toluene in the cyclopentane matrix does not correspond at all to the amounts of toluene ions, which are formed by pre-irradiation. The energy transfer is not caused by a free hole and an electron, but by an exciton. Furthermore, the effect of additives on the fluorescence suggests that the Wannier exciton or mobile ion-pair is responsible for the energy transfer in cyclopentane containing toluene in the solid phase at 77 K.