Chemical and transport processes of photoelectrons generated in rubidium-tetrahydrofuran solutions

The mobility of photoelectrons (mu(e)) was determined by measuring the tran sient photocurrent induced by electron photodetachment from rubidium anions (Rb-) in liquid tetrahydrofuran (THF) in the temperature range of 180-296 K. Electrons were generated by photoexcitation of Rb/THF solutions by 532 n m laser pulses. The measured transients consisted of a fast component (simi lar to 1 mu s) followed by a slow decay (similar to 10-100 mu s). Negative photocurrent was observed at high temperatures and large concentrations of the Rb ions. This unusual behavior is interpreted by taking into account th e recombination and dissociation reactions involving the photoelectrons (e( -)) and rubidium ions (Rb+ and Rb-). The equilibrium constant of electron-c ation dissociation was found to increase by an order of magnitude upon cool ing the Rb/THF solution from 296 to 198 K. The mobility of the photoelectro ns was found to be associated with an activation energy of 5.9 kJ mol(-1).