INTERFERENCES IN RESONANT EXCITATION OF HYDROGENIC CHANNELED IONS

We have observed selection rules for the resonant excitation of swift hydrogenlike ions (Z = 6,7) axially channeled in the [111] direction o f a diamond lattice (silicon). The resonant excitation arises from a c oherent periodic perturbation by the atoms in the bounding crystal row s. We show that the selection rules are the consequence of destructive and constructive interference in the quantum mechanical transition am plitude for excitation.