Quantum beats and level crossing after beam-foil excitation

Alain Denis, J. Desquelles, M. Druetta +1 more

Thomas F. Gallagher

H. J. Andrä

D. A. Church

The cylindrically symmetric beam-foil collision produces excitation and alignment of atom and ion levels similar, but not identical, to that resulting at comparable energies from ion-atom or ion-molecule collisions. When the foil is tilted, the macroscopic change acts on the microscopic scale to produce coherent alignment and orientation of the excited levels. The maximum beam energy range bounding this interaction has not yet been defined. The dynamic interaction which produces these effects is currently not predicted by any theory, although the dynamics of the ions subsequent to the collision are well understood. Refinement of current experimental technique can be expected to better define the final foil surface. The beam-tilted-foil collision promises to be useful in the study of ionic structure via quantum beat, radio-frequency and level-crossing spectroscopy techniques, and may provide a useful probe for certain surface interactions. 4 figs, 48 refs.

H. J. Andrä

A survey on high resolution experiments with atomic systems prepared by the beam-foil or beam-gas interaction is presented. RF-resonance, field-quenching, quantum-beat and level-crossing experiments are described in elementary terms whereas more advanced theoretical techniques are sketched for quantum beats in an appendix.

Donald J. Lynch, C. W. Drake, M. J. Alguard +1 more

Zero-field quantum beats were observed in $\mathrm{L}\mathrm{y}\ensuremath{-}\ensuremath{\beta}$ emission (1026 \AA{}) from hydrogen atoms formed by beam-foil excitation, and the energy dependence of the magnetic-substate cross sections for $n=3$, $l=1$ states was determined for beam energies in the range from 230 to 500 keV/atom.