A comparison of secondary ion mass spectra from keV and MeV ion bombarded vanadium, niobium and copper

Abstract

Positive secondary ion mass spectra have been measured from stainless steel, copper, niobium, and vanadium targets bombarded by 70 MeV 79Br 7+ and 100 keV 40Ar + ions using a modified quadrupole residual gas analyzer. Additional spectra have also been measured from the vanadium target for a number of 79Br and 40Ar projectile energies from 25 keV up to 5 MeV. As has been previously reported [13], under MeV ion bombardment there is an enhancement in the yield of positive ions of electronegative trace constituents relative to the yield of singly charged metal substrate ions. These data suggest that projectiles capable of large inelastic energy deposition may induce secondary ion emission by a mechanism whose contribution to the total ion yield is insignificant or absent when the projectile energy is limited to a few keV. The similarity of these data to recent results in electron- and photon-stimulated desorption is noted.