Field Desorption

Abstract

Field desorption of barium, thorium, oxygen, and some other adsorbates is studied in a field emission microscope with reversed polarity as a function of field strength, temperature and degree of coverage. The desorption occurs in the 100, 200, and 500 million volts/cm range, for the three substances, respectively. At the highest fields the tungsten substrate itself evaporates at room temperature. The quantitative interpretation of the measurements suggests that field desorption be considered as an evaporation of ions in which the energy hump is reduced by the Schottky effect.