Anisotropic excitation by foils and surfaces

Recent theories for the production of orientation and alignment in fast ion excited levels by collision with foils or surfaces have emphasized the development of the excited state from an initial state inside the material defined by a density matrix with particular symmetry properties. Due to the path length inside the material, and to the lesser degree of deflection of the fast ions, the initial states defined by a foil collision will not necessarily have the same character as those defined by a collision with a solid. Coherence measurements of orientation and alignment of excited 0 levels of He, B and N atoms and ions produced by collisions with carbon foils and carbon-coated solids are contrasted to distinguish such differences in final states which may be correlated with the initial distribution of charge and momentum