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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.
