Study of field adsorption using imaging atom-probe field ion microscope. Progress report, April 1, 1981-March 31, 1982

Under a high applied electric field, gas molecules can be field adsorbed on solid surfaces. Field adsorption of noble gas atoms on metal surfaces can occur at a temperature greater than 1000K. The field adsorbed noble gas atoms cannot be field desorbed without also field evaporating the surface atoms. However, they can be desorbed by an additional stimulation from laser pulses. In fact, by employing the time gating technique in the imaging atom-probe, atomic images of Pt and Mo surfaces have been obtained using pulsed laser stimulated field desorption of field adsorbed helium atoms. The direct correspondence of the images produced by thermally desorbed field adsorbed atoms with field ion images support previous calculations, suggesting apex site field adsorption of image gas atoms on field emitter surfaces