Lecture 21 12 11 2006 x ray diffraction xrd theory and analytical technique
1 / 11

Lecture 21 (12/11/2006) X-Ray Diffraction (XRD) Theory and Analytical Technique - PowerPoint PPT Presentation

  • Uploaded on
  • Presentation posted in: General

Lecture 21 (12/11/2006) X-Ray Diffraction (XRD) Theory and Analytical Technique. X-Ray Analysis. X-rays discovered in 1895 Fundamental to understanding of crystal structure and symmetry

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Lecture 21 (12/11/2006) X-Ray Diffraction (XRD) Theory and Analytical Technique

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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Lecture 21 (12/11/2006)X-Ray Diffraction (XRD)Theory and Analytical Technique

X-Ray Analysis

  • X-rays discovered in 1895

  • Fundamental to understanding of crystal structure and symmetry

  • Powder diffraction analyses are a simple and inexpensive method for identifying minerals, especially fine-grained minerals

X-ray Generation

X-rays – High energy*, highly penetrative electromagnetic radiation

*E = hc/λλ(X-rays) = 0.02-100Å (~1)

λ(visible light) = 4000-7200Å

X-ray Vacuum Tube

Cathode (W)– electron generator

Anode (Mo, Cu, Fe, Co, Cr) – electron target,

X-ray generator

X-ray Spectra

  • Continuous spectra (white radiation)– range of X-ray wavelengths generated by the absorption (stopping) of electrons by the target

  • Characteristic X-rays – particular wavelengths created by dislodgement of inner shell electrons of the target metal; x-rays generated when outer shell electrons collapse into vacant inner shells

  • K peaks created by collapse from L to K shell;

    K peaks created by collapse from M to K shell




X-ray Diffraction (Bragg Law)

nλ = 2d sinθ

Defines the spacing (d) of atomic planes and incident angle (θ) at which X-rays of a particular wavelength will reflect in phase (i.e., diffract)

GE+EH = nλ


≠ nλ

Powder Diffraction Method

  • Requires random orientation of very fine crystals

  • Incident beam of a certain X-ray wavelength will diffract from atomic planes oriented at the appropriate θ angles for the characteristic d spacing

  • Random orientation of crystals will produce more intense diffraction peaks for particular angles that correspond to characteristic atomic planes

Powder Diffraction Plots

θ=arcsin (nλ / 2d)

λ(Cu) = 1.54Å

d - Qtz [101] = 3.342

θ = 13.32° ; 2θ = 26.64°


X-Ray Powder Diffraction Records70,000 experimental patterns

Utility of XRD in Chemical ID

XRD Structural State Analyses

Silver Bay anorthosites


Duluth Complex

Anorthositic Series

Silver Bay anorthosites and Duluth Complex

Anorthositic Series analyzed by Miller (1986)

Leveaux Porphyritic Diorite (LPD) analysed by Albers (2006)

(diagram after Smilth, 1975)

Last Lecture 12/13/06

Final Review:

Optical Mineralogy Trivia

  • Login