Resonant coherent excitation of N{sup 6+} and Mg{sup 11+} in planar channeling: Anisotropies in ionization probabilities and x-ray emission [report]

S. Datz, P.F. Dittner, H.F. Krause, C.R. Vane, O.H. Crawford, J.S. Forster, G.S. Ball, W.G. Davies, J.S. Geiger
1994 unpublished
The thrust of the conference in which this paper is presented is toward inelastic interactions of ions with surfaces. The work described in this paper deals with inelastic interactions of ions in planar channeling inside the crystal. We are, however, not too far off the mark because the planar channeling potential is made up from the sum of two (sheet) "surface potentials. The difference, if you will, is similar to that between an ordinary sandwich and an open faced one (smarebrod), and in the
more » ... ebrod), and in the future these techniques may well be applied to the single surface. In earlier work on resonant coherent excitation (RCE) of channeled ions, it was shown that for H-like ions (Z = 4 -9) moving in axial crystal channels in the velocity range 6 vo I vi 5 12 vo, collisional lifetimes are sufficiently long to give well-defined n=l and n=2 states. It was also shown that the effect of the spatially (time) coherent field caused by correlated collisions with atoms arranged in crystal rows can give rise to resonant excitation of the penetrating ion [1,2]. Thus, an ion moving at velocity Vi past a row of atoms with interatomic spacing d experiences periodic perturbation at frequencies v = K(vi/d), K = 1,2,3 ..._ The ion can be resonantly excited when a frequency AEij/h is attained, where Mij is the energy difference between states i and j of the moving ion. We showed that the energy levels of the penetrating ion differed measurably from the vacuum states. These differences reflected the influence of the static crystal field which removed the degeneracy of the 2p" 2py, and 2pz orbitals, and of the influence of wake field which acted to Stark mix the 2s and 2pz states. i
doi:10.2172/10118120 fatcat:kzdju5432vd6tfeilvj2oftzvu