Channeling Phenomena in Crystal Structures

Channeling refers to the guided traversal of charged particles through the regular atomic arrays of a crystal lattice. When a beam of ions or electrons enters a crystal at small angular deviations relative to major crystallographic axes or planes, the collective electrostatic fields of rows or planes of atoms confine the particles to trajectories between atomic strings or layers. This continuum approximation transforms the discrete atomic potential into a smooth, one- or two-dimensional potential well, enabling highly ordered guidance over micrometre scales. Key parameters include the Lindhard critical angle, beyond which particles undergo dechanneling via scattering on individual nuclei, and the crystal thickness, which determines whether steady‐state channeling or transitional scattering regimes dominate. Experimental manifestations encompass planar and axial channeling, mirroring of relativistic electrons, rainbow scattering patterns arising from caustics in the deflection functions, and quantum interference effects that give rise to supernumerary rainbow peaks. Practical applications range from precision beam steering and splitting in accelerator facilities to the production of nanoscale ion beams, isotopic separation, and the study of radiation emission under channeling conditions. Recent advances have extended these concepts to low-dimensional systems such as carbon nanotubes, revealing novel quantum channeling phenomena with potential for materials analysis and nanofabrication.

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Channeling Phenomena in Crystal Structures publication trend

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Technical terms

Channeling: The confinement and guided motion of charged particles along crystallographic axes or planes within a crystal lattice.

Continuum approximation: A model replacing discrete atomic potentials by a smooth averaged potential to describe particle–crystal interactions.

Lindhard critical angle: The maximum incidence angle at which charged particles remain trapped within the planar or axial channels.

Rainbow scattering: A phenomenon where deflection functions produce caustics, leading to sharp maxima in angular distributions.

Half-wavelength crystal: A crystal thickness equal to half the oscillation period of a channeled particle in the planar potential well.

Morse–Maslov index: A phase term in semiclassical approximations accounting for focal points and wave function phase jumps.

References

1. Isotopic effect in half-wavelength-crystal channeling of relativistic ions. Physics Letters B (2020).
2. Quantum Rainbows in Positron Transmission through Carbon Nanotubes. Atoms (2019).
3. Geometrical optics method in the theory of channeling of high energy particles in crystals. Physics Letters B (2019).