Resonant Coherent Excitation of Channeled Ions

We have observed resonant excitation of swift channeled hydrogenlike ions ($Z=5\mathrm{}$ to $Z=9\mathrm{}$) and heliumlike ${\mathrm{F}}^{7+}$ which arises from a coherent periodic perturbation by the atoms in the bounding crystal rows. The resonance excitation was seen through the reduction in the transmission of fixed-charge-state ions through channels in thin crystals of Au and Ag.