Hostname: page-component-586b7cd67f-r5fsc Total loading time: 0 Render date: 2024-11-23T15:32:07.313Z Has data issue: false hasContentIssue false

Differential X-Ray Diffraction by Wavelength Variation: A Preliminary Investigation

Published online by Cambridge University Press:  06 March 2019

M. C. Nichols
Affiliation:
Materials Science Department, Sandia National Laboratory, Livermore, CA 94550; Department of Geosciences, Pennsylvania State University, University Park, PA 16802; Chemistry Department, Lawrence Livermore National Laboratory, Livermore, CA 94550
D. K. Smith
Affiliation:
Materials Science Department, Sandia National Laboratory, Livermore, CA 94550; Department of Geosciences, Pennsylvania State University, University Park, PA 16802; Chemistry Department, Lawrence Livermore National Laboratory, Livermore, CA 94550
Quintin Johnson
Affiliation:
Materials Science Department, Sandia National Laboratory, Livermore, CA 94550; Department of Geosciences, Pennsylvania State University, University Park, PA 16802; Chemistry Department, Lawrence Livermore National Laboratory, Livermore, CA 94550
Get access

Extract

In powder diffraction experiments involving mixtures of compounds, identification of each individual phase is complicated by the presence of other phases. The interpretation of such complex patterns is often very difficult, and much effort has gone into computational search-match algorithms which attempt to identify individual phases (Nichols, 1966; Johnson, 1977; Frevel, 1976). The success achieved by these programs and by manual search-match methods accounts for the fact that X-ray diffractionists have, in the past, not actively searched for other techniques that could be used to simplify such complex problems. In a recent work (Nichols & Johnson, 1980), a comparison was made of the search-match methodologies employed by several similar technologies (mass spectroscopy, fingerprint identification, X-ray diffraction etc.). A significant observation was made that only in the X-ray method was there so much emphasis on analysis of phases in their “as received” condition. In the other cases, emphasis was placed on the separation of phases before obtaining the spectra. A classical example is the GC-MS instrument which employs a gas chromatograph to separate phases before the mass spectrographic analysis is carried out on what are, by that time, essentially pure phases.

Type
VII. XRD Methods and Instrumentation
Copyright
Copyright © International Centre for Diffraction Data 1981

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Frevel, L. K., 1976, Quantitative Matching of Powder Diffraction Patterns, in: “Advances in X-ray Analysis, Vol. 20”, Plenum Press, NY Google Scholar
Johnson, G. G.,Jr 1977, Resolution of Powder Patterns, in: “Laboratory Systems and Spectroscopy”, Marcell Dekker, NY Google Scholar
Klug, H. P. and Alexander, L. E., 1974, “X-ray Diffraction Procedures”, Second Edition, John Wiley and Sons. NY Google Scholar
Nichols, M. C., 1966, A FORTRAN n Program for the Identification of X-ray Powder Diffraction Patterns, UCRL-70078, Lawrence Livermore LaboratoryGoogle Scholar
Nichols, M. C. and Johnson, Quintin, 1980, The Search-Match Problem, in: “Advances In X-ray Analysis”, Plenum Press, NY, Vol 23, p 273 Google Scholar
Nichols, M. C., Smith, D. K. and Johnson, Quintin, 1982, Differential X-ray Diffraction by Wavelength Variation: A Theoretical Basis, Submitted to J. Appl. Cryst.Google Scholar
Smith, D. K. and Nichols, M. C., 1981, A FORTRAN IV Program for Calculating X-ray Powder Diffraction Patterns — Version 9/10Google Scholar
Warren, B. E., 1969, “X-ray Diffraction”, Addison-Wesley, NY Google Scholar