Coherent Excitation of Channeled Ions

Channeled ions passing between ordered rows of atoms in a crystal lattice with a velocity v experience a coherent periodic perturbation of frequencies ¿ = K(v/d), K = 1,2,3,... where d is the distance between atoms in the crystal row. When one of these frequencies coincides with the resonant frequency required to cause transitions in the penetrating ion a resonant coherent excitation (RCE) can occur. In all cases the resonant velocities are slightly shifted from those anticipated from the vacuum levels of the ion because of crystal field effects and under some conditions doublets due to Stark splitting of the line by the wake field are observed.