The Borrmann effect (or Borrmann–Campbell effect after Gerhard Borrmann and Herbert N. Campbell) is the anomalous increase in the intensity of X-rays transmitted through a crystal when it is being set up for Bragg reflection.

The Borrmann effect—a dramatic increase in transparency to X-ray beams—is observed when X-rays satisfying Bragg's law diffract through a perfect crystal. The minimization of absorption seen in the Borrmann effect has been explained by noting that the electric field of the X-ray beam approaches zero amplitude at the crystal planes, thus avoiding the atoms.

References

• Nasonov, Nikolai N. (20 September 1999). "Borrmann effect in parametric X-ray radiation". Physics Letters A. Elsevier. 260 (5): 391–394. Bibcode:1999PhLA..260..391N. doi:10.1016/S0375-9601(99)00545-9.
• Pettifer, Robert F.; Collins, Stephen P.; Laundy, David (2009). "Quadrupole transitions revealed by Borrmann spectroscopy". Nature. 454 (7201): 196–199. Bibcode:2008Natur.454..196P. doi:10.1038/nature07099. PMID 18615080. S2CID 4346649.
• Borrmann, Gerhard; Über Extinktionsdiagramme von Quarz, Physikalische Zeitschrift 42, 157–162 (1941); Die Absorption von Röntgenstrahlen im Fall der Interferenz, Zeitschrift für Physik 127, 297–323 (1950) - original articles on Borrmann effect
• Campbell, Herbert N.; X‐Ray Absorption in a Crystal Set at the Bragg Angle, Journal of Applied Physics 22, 1139 (1951)
• von Laue, Max; Die Absorption der Röntgenstrahlen in Kristallen im Interferenzfall, Acta Crystallographica 2, 106–113 (1949) - original explanation of Borrmann effect