Effect of Low-Energy Ion Bombardment upon Field-Stimulated Exoelectron Emission from Tungsten Surfaces

The field-stimulated exoelectron emission (FSEE) from a tungsten surface bombarded by helium ions with incident energies ranging from 300 to 580 eV was investigated. When a tip was cooled down to 185 K, FSEE was clearly detected at the ion-bombarded tungsten surface with incident energies higher than 500 eV which corresponds to the sputtering threshold of tungsten atoms. A decay of FSEE intensity was also observed after the ion bombardment. In contrast, FSEE was not obvious at the tip temperature of 300 K. These experimental results would be explained by the emission model which is related to a rearrangement of surface tungsten atoms distorted by the ion bombardment.