Energy and angle-resolved studies of neutrals desorbed from ion bombarded polycrystalline metal surfaces

Abstract Angle-resolved energy distributions and energy-resolved angle distributions for atoms desorbed from polycrystalline In and Rh foils bombarded by 5-keV Ar + ions are reported. It is possible to record these data under low dose conditions using multiphoton resonance ionization detection for the neutrals after they have left the target. The results show that angle or energy integrated data agree reasonably well with energy transport theories, an observation confirmed by many previous workers. The energy-resolved angle distributions for both In and Rh, however, exhibit a near cos θ distribution for low energy particles and a near cos 2 θ distribution for the higher energy particles. The angle-resolved energy distributions also exhibit a shift in the peak position to lower values as θ is increased from 0 to 75°. Neither effects are predicted by theory. The results are discussed in terms of the anisotropy of the momentum distribution which apparently exists inside the solid during the evolution of the collison cascade.