Project 14a: Linear Absorbtion Coefficient

for Crystals in [1/cm]

Steffen Weber, July 1998 


see 14b: Quasicrystals

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usage

  1. give the chemical formula in the format 1.Element [SPACE]nAtom [SPACE] 2.Element [SPACE] nAtom [SPACE]...
    the elements can be given in any format (eg: Na na NA for sodium)
    nAtom may be a non-integer value
    The given example is for NaV6O11
  2. give number of formulas per unit cell (may be non-integer)
  3. give unit cell volume [A^3]
  4. click execute

This applet calculates the linear absorbtion coefficient [1/cm] for a given chemical formula and various X-ray wavelengths (Ag,Mo,Cu,Fe,Cr K-alpha).

You can choose between two ways of calculating the linear absorbtion coefficient.
1. using the atomic mass attenuation coefficients
2. using the photon interaction cross sections

For both cases the unit cell volume needs to be provided. The calculated linear absorbtion coefficients are then used to plot a graph, which shows how much an incident beam intensity would be attenuated by passing through a slab of the material (thickness range: 0.0-1.1 mm). You may drag the vertical marker line to facilitate the readout.

The legend lists the various linear absorbtion coefficients, the unit cell mass and the calculated density [g/cm^3].

The data for the atomic mass attenuation coefficients and the total photon interaction cross sections are taken from the International Tables of Crystallography, Vol C, 1992 and are implemented in the code.

wavelengths for K-alpha in Angstrom:
Ag (0.5608), Mo (0.7107), Cu (1.5418), Fe (1.9373), Cr (2.2909)