Compton peak shift in XRF study of graphite

A significant shift from the theoretical position of the Compton peak was observed in a graphite sample using Rh Kα radiation. The magnitude of the Rh KαCompton peak shift depends on both the thickness of the graphite sample and the x-ray beam diaphragm used. The larger the specimen thickness or the beam diaphragm size, the greater is the magnitude of the Compton peak shift. This Compton peak shift is interpreted as being due to the change in the ‘effective’ scattering angle, and it occurs with very light elements only.