[Ifeffit] Problem with Hephaestus at Ca L-edges (Matthew Marcus)

[Matthew Marcus]

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
>
>