Anomalous Scattering Coefficients

Forms interface to plot theoretical values of f' and f"

It is quite easy to plot the values of f' and f" for the element or elements you are interested in over any range of energies from 1000 eV (13 Å) to 25000 eV (0.50 Å). Use the form below to describe the plot you would like to see. By default the plot will span a fairly large energy range; you will probably want to reset this to a much narrower region around the edge of interest.


Elemental absorption edge[s] to plot (use commas to separate elements, e.g.: Se,Pt)
Title for plot:
Energy range in eV (optional) Xmin: Xmax:
Mark X-axis at: CuKa (8014 eV) Elemental absorption edges
Send plot as: PostScript Color PostScript png image ascii gnuplot script

Notes

When you submit a request the information is fed to gnuplot to construct the actual plot. If you have gnuplot installed on your local machine, and also an access path to the relevant absorption edge data files, then you may wish to select instead the "Send plot as: gnuplot script" button above so that you can further customize the plot. More information on using gnuplot via the web is available here.

Where this data came from: The scattering factor data files used to generate plots were calculated using the subroutine library by Brennan and Cowan (see references). The values for f' and f" are derived using the theoretical approximation developed by Cromer and Liberman. This theory gives accurate values far from an absorption edge but does not account for the effects of neighboring atoms, which can be very substantial near an absorption edge. Before conducting an anomalous scattering experiment close to an absorption edge it is therefore advisable to determine the actual scattering behaviour of your sample (see theory v. experiment).
back to X-ray Anomalous Scattering
Ethan A Merritt ©1996-2005/ merritt@u.washington.edu / Biomolecular Structure Center at UW