On 09/24/2015 03:35 PM, Matthew Marcus wrote:
OK. Now I get it. Why use 50eV? Since lifetime and other broadening is not taken into acocunt in any of these tables, why not use a very small number?
Who knows? I wrote that bit of code a long time ago. Whatever the reason was that I chose +/-50 eV -- I am sure it was brilliant! The next release of Demeter will do this much more sensibly, as seen in the attached screenshot. Thanks for bringing this up. B
mam
On 9/24/2015 11:07 AM, Bruce Ravel wrote:
On 09/24/2015 01:43 PM, Matthew Marcus wrote:
See the attached ppt for the demo. I think this gives the whole repeat-by and interpretation. Am I just missing something? That would not be totally surprising.
The algorithms in Hephaestus are pretty dim-witted and tuned (such as they are) to getting the calculations more or less right in the hard X-rays. I don't even try to do calculations in the soft x-ray range correctly. For example, the edge step calculations do the calculation at something like +/-50, which is a very stupid choice for soft x-ray energies. That should explain why L2:l3 ratio is 1. Presumably also why the L1 step is negative!
See, e.g. https://github.com/bruceravel/demeter/blob/master/lib/Demeter/UI/Hephaestus/...
You cannot trust anything Hephaestus has to say about edge jumps below 3-ish keV. Since the +/-50 is hard wired in, the jump ratios will be nonsense for any element for which the energy difference between the L2 and L3 edges is less than 100 eV.
The Delta mu/rho numbers that you cite are interpolated from the Elam (usually) tables and should reliable to whatever extent you consider the table reliable.
B
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-- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 535A Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/
