• 
  Grande, P.L.; Hentz, A.; Schiwietz, G.; Starodub, D.; Garfunkel, E.; Gustafsson, T.: Observation of collective inner-shell effects for protons backscattered from the Al(110) surface. Physical Review A 72 (2005), p. 012902/1-4

10.1103/PhysRevA.72.012902

Abstract:
The surface peak of 98-keV protons backscattered from a clean Al
110 surface has been studied in detail for three different scattering geometries. The corresponding energy-loss distributions are asymmetric due to the single and double ionization of the Al inner-shell electrons
L shell. Effects beyond the independent-electron model
inner-shell collective effects have been observed by using Monte Carlo simulations for the ion ballistic and coupled-channel calculations for the inelastic energy loss. These effects decrease the width by up to 10% for the full width at half maximum. Correspondingly, the low-energy tail of the surface peak is reduced in intensity by more than 30% in the case of a large number of near central collisions as in shadowing and blocking geometries.