Difference between revisions of "X-ray absorption & fluorescence"
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== Absorption Length == | == Absorption Length == | ||
The X-ray beam intensity (of wavelength = | The X-ray beam intensity (of wavelength = Lambda) at depth x into a material is calculated by Beer-Lambert law: | ||
I(x) = e^(-x/ | I(x) = e^(-x/Lambda) | ||
The '''Absorption Length''' is defined as the distance into a material where the x-ray beam intensity has decreased to 1 / e, or about 63% | 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: | This is a convenient value because: | ||
(1/e) = e^(-x/ | (1/e) = e^(-x/Lambda) | ||
ln(1/e) = ln(e ^-x/ | ln(1/e) = ln(e ^-x/Lambda) | ||
1 = x/Lambda | 1 = x/Lambda | ||
Revision as of 00:04, 29 August 2011
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
