Hi guys long time no see, I'm having a small difficulty here in understanding the process. Looking at the equation and the derivation of it, it seems clear that the shift in wavelength can only be caused by the target mass. If we are talking about electron being hit by x-ray, then I take it the choice of atom with which the free electron is bound should then have no effect on the shift. Yet the practice note I have suggested otherwise. If the target is carbon the scattered wavelength decreases by ##\delta \lambda##, but when heavier element is used, such as gold, the scattered wavelength will increase. But this is impossible right? How can the scattered photon acquire energy greater than the original x-ray? In general, should the atom used have any effect on the shift?