The simulation of FIM desorption patterns

Abstract

The lineal features of desorption patterns produced by rapid field evaporation in the field ion microscope, fall on projections of crystallographic zones which correspond to those orientations where bond vectors are parallel to the surface. A method is described for simulating these patterns by computation whereby it is assumed that the trajectory of a desorbing ion is perturbed by forces due to the presence of neighbours on or near the surface. Computed patterns for f.c.c. and b.c.c. structures show many features in common with the experimental patterns for iridium and tungsten. Further refinement would require detailed knowledge of the forces between surface atoms in a strong electric field.