Photoconductivity studies in some nonpolar liquids

Abstract

Measurements of the photoconductivity of liquid n-pentane, n-hexane, cyclopentane, cyclohexane, neopentane, neohexane, and tetramethylsilane induced by far UV radiation (7⩽hν⩽10 eV) have been performed. We have studied the influence of the incident photon energy, of the applied electric field strength, and of the concentration of two electron scavengers (carbon tetrachloride and perfluoromethylcyclohexane). Our results show that in going from the gas phase to the liquid phase, the ionization energy threshold values of these low dielectric constant liquids are lowered by about 1.6 eV. The introduction of an electron scavenger reduces drastically the solvent photocurrent. Our results are consistent with the quenching, by the scavenger, of a solvent expanded excited state, precursor of the geminate ion pair, and not with an epithermal electron scavenging as in high energy photon irradiation.