Injection of photoelectrons into dense argon gas

The injection of photoelectrons into a gaseous or liquid sample is a widespread technique that is used to produce a cold plasma in a weakly ionized system to study the transport properties of electrons in a dense gas or liquid. We report here the experimental results of the collection efficiency of photoelectrons injected into dense argon gas at T = 142.6 K as a function of the externally applied electric field and gas density. We show that the experimental data can be interpreted in terms of the so-called Young-Bradbury model, only if multiple scattering effects due to the dense environment are taken into account when computing the scattering properties and energetics of the electrons.