1 / 13

Instrumental Chemistry

Instrumental Chemistry. Chapter 12 Atomic X-Ray Spectroscopic. Brief Summary. X-ray spectroscopy is a form of optical spectroscopy that utilizes emission , absorption , scattering , fluorescence , and diffraction of X-ray radiation. About X-Rays.

hamish-hartman
Télécharger la présentation

Instrumental Chemistry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Instrumental Chemistry Chapter 12 Atomic X-Ray Spectroscopic

  2. Brief Summary X-ray spectroscopy is a form of optical spectroscopy that utilizes emission, absorption, scattering, fluorescence, and diffraction of X-ray radiation

  3. About X-Rays • X-rays are short-wavelength (hence, high frequency, and hence, relatively high energy) electromagnetic radiation. Two ways to produce X-rays: 1) Deceleration of high-energy electrons 2) Electronic transitions involving inner-orbital (e.g. - d or f) electrons

  4. For analytical purposes, X-rays are generated in three ways: 1) bombardment of metal target with high-energy electron beam 2) exposure of target material to primary X-ray beam to create a secondary beam of X-ray fluorescence 3) use of radioactive materials whose decay patterns include X-ray emission

  5. Schematic of an X-ray tube

  6. Energy-level diagram showing common transitions producing X-rays

  7. Electron beam sources In electron beam sources, X-rays are produced by heating a cathode to produce high-energy electrons; these electrons are energetic enough to ionize off the cathode and race towards a metal anode (the target) where, upon collision, X-rays are given off from the target material in response to the colliding electrons.

  8. TheDuane-Huntlaw The maximum photon energy corresponds to total stopping of the electron and is given by: hvo = (hc)/o = Ve vo is the maximum frequency V = accelerating voltage e = electron charge

  9. X-ray Fluorescence Since X-rays are rather energetic, excitation of sample electrons will give rise to fluorescence as the sample electrons are excited and return to their ground states in a series of electronic transitions.

  10. Bragg equation sin  = (n)/2d = angle of incidence  = wavelength d = interplane distance of crystal

  11. Diffraction of X-rays by a crystal

  12. X-ray monochromator and detector

  13. References http://www.anachem.umu.se/jumpstation.htm http://userwww.service.emory.edu/~kmurray/mslist.html http://www.chemcenter/org http://www.sciencemag.org

More Related