mfisch
Dear Alan
As a similar topic was touched in another post, could you please state a few sentences about the following keywords:
Am I correct that pv_fwhm is the total fwhm of a profile when using peak_type pv? pv_lor would then be the Lorentzian component of this profile whereas 1-pv_lor would be the Gauss part?
If the above is correct, what is the difference between the above keywords and lor_fwhm and gauss_fwhm, i.e. what is the advantage of using the one or the other?
Are both of them convoluted with lg and lh in the emission profile; when are those values needed? If no lh and lg values are known, what are reasonable values, e.g. for synchrotron sources?
Can lg and lh in the emission profile replace any other peak shape description on synchrotron data; thus, lh, lg (from e.g. LaB6) and CS_L/CS_G would be sufficient?
Thanks!
Martin
alancoelho
pv peak type describes a pseudo-Voigt using pv_fwhm and pv_por.
lor_fwhm and gauss_fwhm describe convolutions of a Lorentzian and Gaussian respectively.
Basically what you need to know is that a Voigt is different to a pseudo-Voigt.
lh and lg describe the Lorentzian and Gaussian components of an emission profile line. Use a standard such as LaB6 or Y2O3 to determine the synchrotron emission profile
mogthesprog
I'm refining some data using a pseudo-Voigt peak type. Is it possible to extract the value for the mixing parameter eta?
alancoelho
The keyword pv_lor describes the Lorentzian portion of the pseudo-Voigt; the Gaussian portion is simply 1-pv_lor.
mogthesprog
Thanks for the quick reply Alan.
I'm able to extract one value for the mixing parameter eta by using pv_lor, but since I have two different pseudo-Voigt functions I need to extract the two corresponding mixing parameters. Is this possible?
FYI I'm using two hkl_is phases with a pawley - lebail fit.
alancoelho
>but since I have two different pseudo-Voigt functions I
>need to extract the two corresponding mixing parameters
I don't follow; with two hkl_Is phases then there should be two pv_lor's; ie.
hkl_Is
peak_type pv
pv_lor @ 0.5
pv_fwhm @ 0.5
hkl_Is
peak_type pv
pv_lor @ 0.5
pv_fwhm @ 0.5
Note, it's also possible to write the pv_lor in terms of H, K, L, Th etc... see macros:
PV_Peak_Type
TCHZ_Peak_Type
found in TOPAS.INC