ORIGIN OF THE FIELD-STIMULATED EXOELECTRON EMISSION FROM TUNGSTEN TIPSURFACES

Emission characteristics of the field-stimulated exoelectron emission (FSEE) from tungsten surfaces and the effect of gas adsorption on the FSEE have been investigated. The clean tungsten tip surfaces were prep ared using the field evaporation technique. The clean tungsten surface s thus prepared did not liberate FSEE. Physical adsorption of the resi dual gas atoms at the tungsten surface resulted in FSEE, An obvious en hancement of the FSEE signal due to gas adsorption was observed in whi ch no significant change of the field emission pattern was caused. The refore, FSEE is thus revealed the high sensitivity to the surface cond itions. (C) 1998 Elsevier Science B.V. All rights reserved.