Item

Abstract

Using an isotopic mixture of ²⁰Ne/²²Ne = 1 : 1 as an imaging gas for a tungsten field emitter tip, simultaneous emission of two Ne field ions as well as a small Ne²⁺₂ yield was observed and characterized. The onset of the Ne dimer detection corresponds to an increase in the Ne surface coverage, which suggests that a second adsorption layer may exist. For increasing field strengths above 4 V Å⁻¹ decreasing activation energies of desorption for the surface dimer are obtained as a function of field strength. This gives experimental support for the theoretical calculations of activation energies of field desorption for He, Ne, and Ar adatoms from a tungsten surface.