Anomalous transmission of X-rays in the Bragg case

Conclusion

The influence of the presence of parallel component of polarization on the shape of the rocking curves was proved experimentally in the Bragg case of the 220 reflection of silicon. A kink appeared in a reproducible way on the steep part of the rocking curves.

Theoretical course of the angular dependence of anomalously increased transmission was confirmed by the experiment in the Bragg case.

Experimental value in the maximum of anomalously transmitted radiation was about 1% higher than the corresponding theoretical value. The cause of this discrepancy has not been satisfactorily explained so far.

In spite of the above-mentioned discrepancy the courses of the rocking curves convincingly prove that it is possible to use successfully the effective magnitude of the asymmetry angle in the case of the reflection by the first (collimator) crystal of the double crystal spectrometer. It is convenient to choose the angle between the surface and the diffracting planes higher than the Bragg angle. Then it is possible, by rotating the crystal about the normal to the diffracting planes, to decrease the glancing angle in the interval 〈θ ₀, 0〉 and to adjust in this way the divergence of the reflected X-ray beam to arbitrary required value.