# Project 14a: Linear
Absorbtion Coefficient

## for Crystals in [1/cm]

© Steffen Weber, July 1998

see 14b: Quasicrystals

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**usage**

- 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 **NaV**_{6}**O**_{11}
- give number of formulas per unit cell (may
be non-integer)
- give unit cell volume [A^3]
- 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)