Transverse plane trajectory focusing in axial channelling

The theories of trajectory focusing are used to interpret channelling experiments with 1.7 MeV H+ incident near the <100> axis of MgO. Quantitative explanations are found for the following phenomena: deviations from circular symmetry in the axial channelling dip, high dechannelling during the transition from axial to planar channelling, the anomalous values of backscattering maxima in directions between low-index planar channels just outside the axial dip and the onset of channelling within narrow planar channels farther away from the axis. Agreement is also excellent with dechannelling data around <100> W, with simulated dechannelling data around <110> Al, and other axial to planar channelling transition data available in the literature. The success of the focusing theory makes it suitable for interpreting lattice site location studies in the future. (author)