25:26 How does the polarization cause the dip in the curve? Thank you for the nice talk.

@user-sk5fw3ux8j

24 күн бұрын

Thank you for your question. The X-ray source for laboratory total diffraction measurements is usually considered to be unpolarized, which is mostly true even when incident mirror optics are used such as in the Rigaku SmartLab and Synergy systems. Conceptually, you can think of an unpolarized X-ray source as being made up of an equal amount of X-rays polarized in two orthogonal directions. For reflection measurements, we usually think of one of the orthogonal directions as being normal to the sample surface and the other in the plane of the surface. In the same way that light is polarized on reflection from water, the X-ray polarized normal to the sample surface will be preferentially absorbed dependent on the diffraction angle and for diffraction angles of 90° 2θ will be completely absorbed. Simplistically, at 0 and 180° 2θ there is no preferential absorption, and the X-ray intensity will be 100%. While at 90° 2θ, the normal polarized X-rays are completely absorbed reducing the X-ray intensity to 50%. This gives a dip in the measured total diffraction intensity as a function of 2θ. This does not apply to synchrotron sources that are already plane polarized or when you use an incident beam monochromator with large Bragg angle. Please feel free to contact us if you would like to discuss it more: rigaku.com/talk-to-an-expert

@DW-iq8lt

24 күн бұрын

@@user-sk5fw3ux8j Your answer is beautifully detailed. Thank you.