Coherent Excitation of Ionic States by Correlated Collisions in a Crystal Lattice

Abstract

Ions moving through crystals at small angles with respect to atomic rows and planes undergo correlated collisions which confine their motion (“channeling”). Well-channeled ions collide only with conduction electrons, For ion velocities v_i ≫ v₀ ionization is similar to electron bombardment at v_e = v_i. The ion passing the atoms spaced at a distance d in the crystal rows experiences a coherent perturbation of frequency v_i/d and may be resonantly excited at (v_i/d) = ΔE_ij/h. This is seen in an enhanced ionization probability. The relation of this effect on the states of the penetrating ions and the crystal fields is discussed.