Yoneda peak

Yoneda peak (also Yoneda–Vineyard peak) is an enhancement in scattering intensity from scattered radiation propagating as an evanescent wave underneath a surface or another material interface. It appears under an exit angle αf that is close to the critical angle for total external reflection αc. For x-rays and neutrons, critical angles are small. The Yoneda peak is typically observed in off-specular reflectometry and in grazing-incidence small-angle scattering (GISAS), where it is also used for calibration. The phenomenon was described by Yasuharu Yoneda in 1963[1] and later given a rigorous theoretical foundation by George H. Vineyard.[2]

Off-specular scattering from a model system, consisting of dense disks on a substrate. The strong Yoneda peak appears as horizontal and vertical bands at a critical angle of 2 degrees. To keep the figure simple, the substrate was chosen to have the same average scattering-length density as the decorated layer. Simulated with BornAgain.[3]

References

  1. ↑ Yoneda, Y. (1963). "Anomalous Surface Reflection of X Rays". Physical Review. 131: 2010–2013. Bibcode:1963PhRv..131.2010Y. doi:10.1103/PhysRev.131.2010.
  2. ↑ Vineyard, G. H. (1982). "Grazing-incidence diffraction and the distorted-wave approximation for the study of surfaces". Physical Review B. 26 (8): 4146–4159. Bibcode:1982PhRvB..26.4146V. doi:10.1103/PhysRevB.26.4146.
  3. ↑ Scientific Computing Group of Forschungszentrum Jülich at JCNS Garching. BornAgain, open-source research software to simulate and fit neutron and x-ray reflectometry and grazing-incidence small-angle scattering. Online documentation page Yoneda Peak, https://bornagainproject.org/git-develop/ref/sim/class/offspec/yoneda.
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