X-ray absorption & fluorescence

X-ray Absorption Information (11BM page) http://11bm.xor.aps.anl.gov/absorption.html

Absorption Length

The X-ray beam intensity (of wavelength = Lambda) at depth x into a material is calculated by Beer-Lambert law:

I(x) = e^(-x/Lambda)

The Absorption Length is then defined as the distance into a material where the x-ray beam intensity has decreased to 1 / e, or about 63%. (alternatively called Attenuation Length). Recall that e = 2.718.

This is a convenient value because:

(1/e) = e^(-x/Lambda)

ln(1/e) = ln(e ^-x/Lambda)

1 = x/Lambda

x = 1/Lambda

and 

x = 1/mu

Links

• Absorb: compute X-ray absorption for powder XRD capillary samples (11BM page)

• MuCal: calculate X-ray absorption, fluorescence and more (by C. Segre @ IIT/ANL)