The intrinsic photoconductivity of liquid zenon

Abstract

Photoconduction in liquid xenon has been measured as a function of photon encrgy E. light intensity I, and electric field F . In the transparent region E < 7.7 eV photo-currents exist due to ionization of impurities. In the strongly absorbing region 7.7 < E < 8.9 eV only small photocurrent exist: they arc attributed to ionization of impurities by excitons which are directly created in this region. In the strongly absorbing region E > 8.9 eV large photocurrents exist: they are attributed to direct creation of electrons and holes with a quantum efficiency of at least 25 %, Thus the single particle band gap is directly determined to be 8.9 eV, which is in agreement with the gap expected from current intei-pretations of condensed rare gas spectra. All currents are linear in I. From the dependence nnF it is shown that an unbound electron hole pair created by a photon E > 8.9eV mal subsequently recombine with each other and not contribute to the current. The criteria for such self recombination. which can play a large r61e in the observation of photoconductivity, are discussed.