Premature field evaporation in the atom probe

Abstract

The motion of ions evaporating in the subnanosecond period before a pulse has matured is invoked in the interpretation of resolution limiting energy deficits in the TOF atom-probe. The second order, nonlinear differential equation of motion in the time and space dependent field is numerically solved by computer. Two shapes of the pulse front, in which the final voltage level is approached either from below or from an overshoot are considered. The latter case accounts for the actual observations by giving the proper magnitude and mass dependence of the energy deficits.