Electron emission 8 Ions 6 Protons 6 Aluminum 4 Approximation theory 4 Ion-surface collisions 4 Ionization 4 Lithium compounds 4 Mathematical models 4 Surface phenomena 4 Angular distribution 2 Atom-surface collision 2 Atomic bound states 2 Atomic ionization 2 Atoms 2 Band structure 2 Charge state 2 Coherence-length 2 Convoy electrons 2 Crystals 2 Energy dissipation 2 Focusing 2 Free electron gas 2 Glancing angles 2 Ground state 2 Hydrogen 2 Impact velocities 2 Ion surface collision 2 Ion-surface collision 2 Ionization of solids 2