Excited radical cations

Electron transfer may also dominate the excited state chemistry of open shell radical ions. The fluorescence of the radical anions of anthraquinone and 9,10-dicyanoanthracene and the radical cation of thianthrene are quenched by electron acceptors and donors, respectively, although detailed kinetic analysis of the electron exchange do not correspond exactly either with Weller or Marcus theory (258). The use of excited radical cations as effective electron acceptors represents a... 

Depke, G. Lifshitz, C. Schwarz, H. Tzidony, E. Non-ergodic behavior of excited radical cations in the gas phase, Angew. Chem. Int. Ed. Engl. 1981,20, 792-793. 

To conclude, we have established the role of intricate nonadiabatic coupling in the dynamics of electronically excited radical cations of PAH. The theoretical results presented above support the experimental data on ultrafast nonradiative decay and... 

When cellulose is irradiated in vacuo G(H2) = 3, G(C02) = 6 and G(CO) == 1 x 10 mol J have been observed [99]. The gaseous products CO and CO2 are ascribed to the decay of highly excited states (excited radical cations). It is noted that CO formation is also of some importance in the radiolysis of alcohols in the liquid and frozen state [102, 103]. However, for CO2 and CO, a free-radical pathway starting with the P-fragmentation of the oxyl radical 80 [reaction (59)] is also conceivable, as one expects the radicals in the solid to have a long lifetime due to a reduced mobility, which could selectively permit reactions (60) - (64) to occur. 

Molecules will be directly ionized to become excited radical cations (RH2" ) or radical cations (RH2+), or super-excited molecules (RH2 ) will be produced by the ionized radiation. Super-excited molecules will dissociate into radicals, small molecules, or ions or dissipate their energy to become excited (singlet or triplet) molecules (RH2 )- Excited radical cations will dissociate into radicals, molecules, and ions or be deactivated as radical cations. Not only the dissociation but also geminate recombination with electrons to produce excited molecules and ion-molecule reaction are significant processes for radical cations. Excited molecules will dissociate into radicals or small molecules or be deactivated to the ground state. Electrons produced by ionization will be thermalized by collision with solvent molecules. Thermalized electrons will be neutralized by geminate recombination with radical cations or solvated. These processes will occur in the spur within several picoseconds at room temperature. 

When an organic solution is irradiated, most of the radiation energy is absorbed by solvent molecules. Because energy transferred to molecules is distributed around 20-40 eV, the activated species, such as super-excited molecules, excited radical cations, electrons, etc., are the initial products in a spur. Radicals, cationic species, and solvated electrons are produced from these initial species. Though some of these species will be lost by geminate recombination, others that have escaped from the spur can react with the solvent and solute molecules. 

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