F. Aumayr et al., EMISSION OF ELECTRONS FROM A CLEAN GOLD SURFACE-INDUCED BY SLOW, VERYHIGHLY-CHARGED IONS AT THE IMAGE CHARGE ACCELERATION LIMIT, Physical review letters, 71(12), 1993, pp. 1943-1946
Total low-energy electron yields for the normal incidence interaction
of slow very highly charged ions (Xe-136q+, 21 less-than-or-equal-to q
less-than-or-equal-to 51; Th-232q+, 51 less-than-or-equal-to q less-t
han-or-equal-to 80) with a clean gold surface have been determined fro
m the related measured electron emission statistics. The projectile im
pact energies could be reduced down to the image charge acceleration l
imit. The electron emission yield was found to increase proportionally
with the increasing projectile charge state in all cases studied, sug
gesting no saturation in the ability of the Au target to provide neces
sary electrons within the above surface interaction time (e.g., about
280 electrons/projectile for Th79+ in less than 10(-13) s). Because of
the relatively narrow energy distribution and very high charge states
of the incident ions, the first clear measurements of image charge ac
celeration from electron emission yields could be performed. Results o
f a quantitative study of this acceleration are in good agreement with
those of a theoretical model recently developed by J. Burgdorfer et a
l.