TAN, ALDRIN A. April 01,20162015-89741MSE 225 ( X-ray Crystallography and Spectrography)Dr. Alberto Amorsolo Jr.Reflection Paper #4

In the previous lecture we describe the interaction of x-rays with electrons such as bound electrons, free electrons and loosely bound electrons. We also describe the interaction of X-rays and its mechanism with the atom on materials and initially identify the factors that may possibly affect the intensity of the scattered x-ray at a given point in space. I learned that positions of atoms in the unit cell affect the intensities but not the direction of the diffracted beams. To elaborate further we initially discuss the scattering of x-ray by an electron. Due to the acceleration or deceleration of an electron an electromagnetic wave is emitted and an electron which has been set into a certain oscillation due to the X-ray bombardment will continuously accelerating and decelerating when it is in motion and therefore emits electromagnetic wave. Those scattered beam was the outcome of the radiation of the electron by the incident beam and this beam has the same wavelength and frequency as the incident beam and therefore coherent or almost the same with it. During the scattering a phase change may occur from an electron describe as λ/2 and said to be the same for all directions in a crystal and later will cancel out in any considerations of the phase differences between the rays that is scattered by different atoms. Depending on the scattering angle intensity of the beam may vary and it was defined by J.J. Thomson the intensity I = I0(Kr2)sin2α. I also learned that when X-rays encounter loosely bound or free electrons an occurrence of Compton Effect can be observe see figure below

And when we treat these rays as photons with a certain energy hν 1, collision of an x-ray photon with an electron is similar to elastic collision between two billiard balls. However I have one question regarding this Compton effect because as we have discuss there are undesirable Compton effect that may occur on the diffraction background of the diffraction pattern my question is how we could possibly avoid of having this undesirable Compton effect? And if it is not avoidable how could we decrease of having this darkening in the background.