Nj. Sack et al., DEPTH OF ORIGIN OF ESD IONS - ENHANCEMENT OF F- FROM PF3 RU(0001) UPON PASSAGE THROUGH XENON OVERLAYERS/, Surface science, 334(1-3), 1995, pp. 695-700
We have studied the electron stimulated desorption of F- from a monola
yer of PF3Ru(0001); the ions pass through ultrathin overlayer films of
Xe. Surprisingly, we find the F- yield to be 4 times higher in the pr
esence of a Xe overlayer one monolayer thick than in the absence of Xe
. This enhancement is accompanied by a dramatic change in the ion angu
lar distribution: While F- ions desorb from PF3Ru(0001) in a hexagonal
array of off-normal beams, they desorb in a broad normal distribution
in the presence of a Xe overlayer. We discuss a model which attribute
s the increase in F- to a decrease in the neutralization probability o
f F- with the surface, and the change in angle to elastic scattering.