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?
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/Formulas.pm#L274
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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