Characteristics of the Slow Conductivity Signals of Pyrene Produced by Pulsed Laser Irradiation in Non-Polar Hydrocarbon Solvents

Conductivity signals induced by pulsed laser irradiation of pyrene in non-polar hydrocarbon sol-vents consist of fast signal (first few milliseconds) associated with electrons and a slow signal (after some milliseconds) with ions. Characteristics of the slow signal have been investigated by changing the laser pulse energy, the bias voltage, the electric field, the eiectrode spacing and the irradiation position. The time profile of the slow signal was affected by space charge effects and by competition between interionic recombination of ions and their escape from the irradiation region. 1. I"ntroduction Dynamics of electrons, ions, and geminate ion-electron pairs produced in pUlse radiolysis,') have been the subject of many experimental and theoretical studies, but those in photoionization remain almost unexplored. The pulsed laser photoionization technique makes it possible to ionize one solute selectively by appropriately choosing the excitation wavelength and to produce charged species at a specified region in a solution. The con-ductivity measurement is a simple and sensitive technique. Thus, the conductivity signal produced by photoionization will offer valuable information about dynamics of electrons, molecular ions, and geminate ion-electron pairs