Photoionization Current by Vacuum Ultraviolet Light in N₂/O₂ Mixtures

Abstract

Measurement of photoionization current is carried out in N 2 /O 2 mixtures using a gas cell, which is made up an eccentric cylinder electrode. A deuterium discharge lamp with MgF 2 window is used for vacuum ultraviolet source. The photon energy of the VUV is changed by CaF 2 and quartz filters. The photoelectron current emitted from the surface of electrodes is observed in pure N 2 gas. On the contrast, it is confirmed that photoionization current increased in the gas cell with an increase in the partial pressure of O 2 in N 2 /O 2 mixtures. Such current is also found in UV region. These facts prove certain generation processes of charged particles by photo ionization of NO which is formed through the recombination from dissociated O and N atoms by the VUV absorption. However, another result suggests a possibility of a certain charged particle production process through the interaction between N 2 and photodissociated O atom.