How to correlate two XRD data from synchrotron and from Cu as energy source?
Dear Hasna,
correlation is done via the Bragg law:
lambdaCu = 2* dhkl*sin(thetahkl;Cu)
and
lambdaSyn = 2* dhkl*sin(thetahkl;Syn)
for 'Cu as source' the Cu k-alpha radiation is used: lambdaCu = 1,5406A;
for the synchrotron based XRD please use the x-ray wavelength lambdaSyn, which was set up by the monochromator for these scans.
The positions thetahkl (2thetahkl) of the XRD peaks at the theta (2theta) axis are scaled by the wavelength in use.
In "traditional" XRD using a Cu(Kalpha) source, the diffraction pattern gives the position of the diffraction peaks as a function of teta (or 2 teta), whereas when using synchrotron radiation the diffraction pattern gives the position of the diffraction peaks as a function of energy.
In both cases, the interplanar distance (d) is given by Bragg's law, as Dr. Martens explains; however, it must be adequately written:
For "traditional" XRD: 2*d*sin teta (variable)= lambda (fixed)
For synchrotron XRD: 2*d.sin teta (fixed) = lambda (variable)
as E(keV)= 12.4/lambda (Å), then
2*d.sin teta (fixed) = lambda (variable)= 12.4/E or
E*d*sin teta (fixed)=6.2 which is more frequently used.
As the value of "d" is the same in both equations, then:
lamba (fixed)/2*sin teta (variable) = 6.2/E*sin teta (fixed) or
E = 12.4* sin teta (variable) / lambda (fixed) * sin teta (fixed)
So you can transform the diffraction pattern from one technique to another.
Best regards,
Pedro
P. Grima Gallardo Hi, Gallardo. so if i want to convert the synchrotron XRD data into conventional XRD (Cu K) data, what should i do? is there any suggestion? thank you.
It is very easy. You must adapt Bragg equation 2d sin(theta) = lambda for each experiment since for traditional XRD measurements lambda is fixed, whereas for synchrotron lambda is variable:
Traditional XRD: 2d sin (theta variable)=lambda (fixed) or 2d=lambda (fixed)/sin (teta variable)
Synchrotron: 2d sin (teta fixed) = lamda (variable) or 2d=lamda (variable)/sin (teta fixed). As the term 2d is identical for both expression, then:
lambda (fixed)/sin (theta variable)=lamda (variable)/sin (teta fixed)
If you have synchrotron data:
sin (theta variable)= lambda fixed/lamda (variable)/sin (teta fixed)
Lambda fixed and sin (theta fixed) are parameters of the experiment whereas lambda variable is obtained from E (variable) using the expression E(keV)=12398/lambda(Å).
P. Grima Gallardo Dear Gallardo, this really helps. And have successfully done it in highscore plus. Thank you.
Thank you, Yongtie. If you like my answer please don´t forget to recommend.
P. Grima Gallardo @ Sir, you are talking about synchrotron XRD data colleceted in energy dispersive mode. If we fix the wavelength, then we can collect XRD pattern with theta as variable (Bragg's law)
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