IF you use EXPGUI graphical interface, when you build an experiment, adding a new istogram (powder pattern), you have to select an instrument parameter file. For a conventional diffractometer, an example of this file is inst_xry.prm, and can be found in the /gsas/example subdirectory. You can select this and then change some parameter inside, by clicking on the "edit file" near the "instrument parameter file" section of the "add new istogram" window. A new window with some instrumental parameters will open. You can check if they fit your instrumental setup, especially the radiation type, number and values of wavelengths, and polarization. Other parameters, such as zero shift, or profile parameters, can be refined subsequently during the refinement procedure.

The k-alpha2 will be handled automatically iif you configure the software correctly.

IF you use EXPGUI graphical interface, when you build an experiment, adding a new istogram (powder pattern), you have to select an instrument parameter file. For a conventional diffractometer, an example of this file is inst_xry.prm, and can be found in the /gsas/example subdirectory. You can select this and then change some parameter inside, by clicking on the "edit file" near the "instrument parameter file" section of the "add new istogram" window. A new window with some instrumental parameters will open. You can check if they fit your instrumental setup, especially the radiation type, number and values of wavelengths, and polarization. Other parameters, such as zero shift, or profile parameters, can be refined subsequently during the refinement procedure.

Thanks for Edward Payzant. This positive answer is just what I want!

And the instruction by Riccardo Vivani is helpful for me, a beginner.

1. Yes, Ka1 and Ka2 are automatically calculated in GSAS and any other software.

2. It is not strongly not recommended to remove Ka2 for Rietveld refinement as latter does much better job in accounting for Ka2 as any removal software.

When you Keep Ka1 and Ka2 ou multiply by 2 the number of data in your refinement, so you not only improove your refinements results but also you reduce the standards errors on refined values. Yes it's strongly recommanded to keep Ka1 and Ka2. Unless you are proceeding to index a cell you need to strip Ka2 and keep only the stronger one Ka1.

I agree with Peter Zavalij. It is BETTER done without stripping (rather than to remove) K-alfa 2. I had bad experience in refining after K-alfa stripping. As said by others, GSAS takes care of it. If you intent to refine K-alfa1 to -alfa 2 ratio, check that the ratio is meaningful.

It may be useful to refine the k alpha 1/k alpha 2 ratio using a standard when analyzing data collected using a diffracted beam monochromator. The ratio can change depending on how well the monochromator is aligned.

In general Ka1 is only used and ka2 is removed automatically by the software in most of the softwares by selecting parameters. However, it is better to first optimized the ratio by using a standard sample ( generally silica) and than go ahead with refinement. The number of counts ( diffracted energy) also affects the quality of refinement using reitveld. Thus, higher energy tube is recommended if the XRD data are to be refined.

Parmendra - a few clarifications:

(1) these days the usual practice is to fit the full pattern (both Ka1 and Ka2) rather than to create data artifacts from the Ka2 stripping

(2) unless you are using a monochromator the Ka1:Ka2 ratio is not likely to differ from the literature, though it certainly cannot do any harm to verify this

(3) of course the counting errors are important, but the number of counts is not simply a function of the "energy" of the tube - for example, counting longer might accomplish the same goal. By "energy" I am assuming that you are referring to the current and voltage settings on the tube, since the x-ray line energy is fixed.

I have to agree that removing the Ka2 is not a good idea. Any time you manipulate your data set, you are essentially removing any confidence in the statistical validity of the method. Can you get reasonable results, probably, but you are more likely to introduce errors into your system.

As mentioned above, you can either use literature values for the Ka1/Ka2 ratio - or better - use a known standard (NIST SRMs - Alumina plate, LaB6, Alumina powder or silicon all are useful materials) to characterize your instrumental performance/conditions prior to running samples and input those parameters into your instrument parameter file. This also aids your refinements by giving you a starting point much closer to your instruments actual peak shape (rather than the generic starting point).

yes can you automatically calculated in GSAS the Kalpha1 and Kalpha2

You can use any software like GSAS or FULLPROF for refinement. Software is immaterial here. Use should prepare your instrument file carefully in which you have to incorporate the ratio between Ka1 and Ka2. It will take care during refinement. You need not remove Ka2 from your XRD data.

I agree with other no need to do correction on the X-ray diffraction profile when you use GSAS or other program

do we reqiure to remove the K alpha 2 if we perfom refinement through FULLPROF?

Here is another discussion regarding the presence of K Alpha 1 & K Alpha 2 in conventional diffractograms.

Fundamentally speaking,

A. Is it a "boon" or a "curse", depends on how much you want to know about XRD?

B. Are you fearful of "lemons" or do you like making "lemonade"?

C. Is the presence of K Alpha 2 an internal calibration tool for diffractograms or just an annoyance in XRD worthy of "removal", "stripping" and "elimination"?

http://www.linkedin.com/groupItem?view=&gid=2683600&item=5843613667337195520&type=member&commentID=5850000393718763520&trk=eml-ntf-hero-like-my-discussion-cmt&midToken=AQE3VAZtsHNG3g&ut=3SGPiJp9EFLm81#commentID_5850000393718763520

"Thinking out-of-the-box" in XRD: http://www.flickr.com/photos/85210325@N04/10659886546/

1. Keep the K α1 α2 Doublet, use Matteo Leoni's reference for WPPM (Whole Powder Pattern Modeling):

http://www2.fkf.mpg.de/xray/CPD_Newsletter/cpd28.pdf

2. For "stripping", "removing" etc. use the age old conventional method for the K α1 α2 Doublet:

Journal of Scientific Instruments Volume 25 Number 7

W A Rachinger 1948 J. Sci. Instrum. 25 254 doi:10.1088/0950-7671/25/7/125 "A Correction for the α1 α2 Doublet in the Measurement of Widths of X-ray Diffraction Lines "

3. Use the whole instrumental profile by calibrating with a "known standard sample"