The high temperature and field treatment of the tungsten tip in a field emission microscope and the adsorption of oxygen and hydrogen

The adsorption of hydrogen and oxygen on the clean surface of tungsten obtained by thermal desorption of impurities from the tip in FEM and on the surface of a tungsten tip formed at a high temperature under the influence of a high voltage was studied. It could be deduced from the experiments that at 78‡K even the adsorption heat of oxygen is not sufficient for the surface layers of tungsten to be rearranged. The influence of temperature and an electric field on the emission pattern of the tip and its shape was also studied.