Field desorption of Potassium from (001), (011) and (112) Tungsten planes

Field desorption of potassium from the (001), (011) and (112) tungsten planes in the temperature range 80–140 K and in the field range 0.10–0.55 V/Å has been investigated using the field emission micrscope with Faraday cage and a rotatable emitter. Generally good agreement with the results, obtained previously by other authors for other adsorbates and for the whole emitter tip, was found. However the temperature dependence of the desorption field is different for some crystal planes. The binding energy at zero coverage and zero field was determined. The values of 1.95 eV, 1.75 eV and 2.0 eV were obtained for the (001), (011) and (112) planes, respectively. The degree of desorption was also measured as a function of desorbing field and a significant difference of this dependence for the (001) and (011) planes was found.