Xray::...ceEXAFS(3pm)

💖 Xray::...ceEXAFS(3pm) 💖

okay bestie so this is a page from the User Contributed Perl Documentation, and it's literally called Xray::...ceEXAFS(3pm) — the vibes are immaculate, the name is a little mysterious, we move.

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✨ NAME ✨

Ifeffit::Demeter::FluorescenceEXAFS — corrections for fluorescence EXAFS data 🦋

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🌸 DESCRIPTION 🌸

So basically this class hands you class methods that compute corrections to fluorescence EXAFS data for the effects of normalization, I0, and self-absorption. And the way it does that? It pulls x-ray absorption coefficients from the Xray::Absorption package. iconic. no cap. 💅

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🎀 METHODS 🎀

heads up bestie: the values that come back from every single one of these methods depend on the data resource you're using. go look at Xray::Absorption for the tea. ☕

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⭐ "mcmaster"

It's called "mcmaster" for historical reasons — we don't ask questions, we just respect the lore. This one calculates the normalization correction for a given element. 💜

$sigma_mm = Xray::FluorescenceEXAFS->mcmaster($element, $edge);

It takes the central atoms tag and the alphanumeric edge symbol as arguments, and it returns the normalization correction in units of Angstrom squared.

"normalization" and "edgestep" are aliases for this method. slay, three names, one function, main character energy fr fr. 👑

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🌈 "i0"

This one calculates the correction due to the I0 fill gases in a fluorescence experiment. 🫶

$gases = {nitrogen=>$nitrogen, argon=>$argon, krypton=>$krypton};
$sigma_i0 = Xray::FluorescenceEXAFS->i_zero($central, $edge, $gases);

It takes the central atoms tag, the alphanumeric edge symbol, and a reference to a hash containing the volume percentages of the three gases as arguments. It assumes that any remaining volume is filled with helium, and it correctly accounts for the fact that nitrogen is a diatom (not me remembering your chemistry for you 😭). It returns the I0 correction in units of Angstrom squared.

"i_zero" and "izero" are aliases for this method. two aliases, so many nicknames, so little time. ✨

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🦋 "self"

This one calculates the correction due to self-absorption in a fluorescence experiment. It assumes that the sample is infinitely thick and that the entry and exit angles of the photons are the same. 📐

$contents = {Y=>1, Ba=>2, Cu=>3, O=>7};
($amp_i0, $sigma_i0) = Xray::FluorescenceEXAFS->self($central, $edge, $contents);

It takes the central atoms tag, the alphanumeric edge symbol, and a reference to a hash which counts the atoms in the unit cell. It returns a list — and listen, the order matters bestie — whose zeroth element is the multiplicative amplitude correction and whose first element is the sigma^2 correction in units of Angstrom squared. 🍓

"overabsorption" is an alias for this method. (the original says "aliases", plural — we love a typo moment, we keep it exactly as it is 💖)

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💀 BUGS AND LIMITATIONS 💀

okay not to be dramatic but here's the part where we hold hands:

• Fourth cumulant corrections are not calculated. just. not there. 🫠
• Geometry and thickness effects are not included in the self absorption calculation. nope, not in there either.

Please report problems to Bruce Ravel (bravel AT bnl DOT gov) 🙏

Patches are welcome. literally please, the door is open, come thru. 🚪✨

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👑 AUTHOR 👑

Bruce Ravel (bravel AT bnl DOT gov)

http://cars9.uchicago.edu/~ravel/software/

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🎀 LICENCE AND COPYRIGHT 🎀

Copyright (c) 2006-2008 Bruce Ravel (bravel AT bnl DOT gov). All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 💀 no promises bestie, it's giving "as is" energy, and that's the law.

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and that's the whole page!! 🌈 this lil beauty is from perl v5.34.0, dated 2022-06-28, and it's filed under Xray::...ceEXAFS(3pm) in the User Contributed Perl Documentation. go forth and correct your fluorescence EXAFS, bestie — you got this. mwah 💋💖