Eur. Phys. J. AP 19, 15-24 (2002)
https://doi.org/10.1051/epjap:2002044

Thermionic emission and photoemission of electrons from dielectric and metal surfaces in Cs vapor cells

Laboratoire Kastler Brossel (Laboratoire de l'École Normale Supérieure et de l'Université Pierre et Marie Curie, associé au CNRS (UMR 8552)), Département de Physique de l'École Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France

Corresponding author: marianne@lkb.ens.fr

Received: 19 December 2001
Accepted: 4 April 2002
Published online: 28 June 2002

Abstract

We have studied the electrical conductivity of Cs vapor cells in the temperature range 190−270 °C with Cs atom density up to 3 × 10¹⁴ cm⁻³. Depending on these parameters controlled independently, two predominant mechanisms are shown to determine the electrical properties of the cells: wall surface conductivity and space conductivity. The latter is caused by thermionic emission of electrons from the “cesiated” surface at submonolayer coverage. This process has been studied for the case of metal (Ti) and dielectric (Al₂O₃) surfaces. The values of the electron emission work function are found to be 1.38–1.42 V for Ti, 1.4–1.45 V for alumina and 1.39 V for sapphire. From independent photoemission studies, we also obtain the value of 1.35–1.40 V for the work function of sapphire. Our measurement technique not requiring internal electrodes can easily be implemented for studies of charge emission and ionization, in different types of dielectric cells containing a low density gas medium.