Photoconductivity caused by the photoexcitation of geminate electrons in nonpolar liquids

Abstract

Photocurrent transients arising from the pulsed photoexcitation of electrons trapped near their parent cations (geminate electrons) in liquid methylcyclohexane were observed in the nanosecond-microsecond range at the temperatures 150-200 K. The time profile of the photocurrent was found to have a significantly different kinetics from that observed in the case of photoexcitation of free electrons, i.e., electrons far removed from the Coulomb center. The diffusion model of the motion of the electrons near the sibiling cations was used to describe quantitatively the photocurrent kinetics observed. It is concluded that studies on the photoconductivity caused by the photoexcitation of geminate trapped electrons offer an approach to the measurement of thermalization distances of low-energy electrons in nonpolar organic liquids.