The Borrmann effect (or Borrmann–Campbell effect after Gerhard Borrman and H. 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.
- 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.
- G. Borrmann, Phys. Zs. 42, 157 (1941); Z. Phys. 127, 297 (1950) - original articles on Borrmann effect
- M. von Laue, Acta Cryst. 2, 106 (1949) - original explanation of Borrmann effect.