Mise en évidence de la dispersion anormale par mesure de l'indice d'un prisme à l'aide de la double diffraction des rayons X

The refractive index, n, for X-rays is measured by interposing a prism in the path of X-rays falling on a perfect silicon crystal at the Bragg incidence angle. Owing to the deviation angle of the prism, the separation of the two wave fields excited in the silicon crystal is modified, from which the value of n − 1 can be deduced with a 1% accuracy. The method has been applied to the measurement of the anomalous dispersion correction for the refractive index of zirconium for Mo Kα.