Are there examples of UV-Vis emission from charge-separated states? The cases I have encountered have only absorption. Is the recombination process of a nonradiative kind by necessity?
Asked
Active
Viewed 75 times
1 Answers
3
There are at least cases in which charge recombination results in an excited species that deactivates via fluorescence.
Imagine the ionization of a hydrocarbon ($\ce{RH}$) to yield a radical cation and a solvated electron. \[\ce{RH ->[\mathrm{e-beam}] RH^{+\cdot} + e-}\]
Trap the electron by reducing an aromatic hydrocarbon ($\ce{ArH}$) to the coresponding radical anion.
\[ \ce{ArH +e- -> ArH^{-\cdot}}\]
Charge recombination between the radical cation and the radical anion can yield $\ce{ArH}$ in an excited state.
\[\ce{RH^{+\cdot} + ArH^{-\cdot} -> RH + ArH^{\ast}} \]
Back in the days, Alexander D. Trifunac did a lot of work on that at ANL.
Klaus-Dieter Warzecha
- 43,925
- 8
- 100
- 164