To add to what Robert said... Section 12.2.3 of Scott Calvin's textbook, XAFS for Everyone, may be exactly what you are looking for. You can find it on Amazon and elsewhere. I am not sure if you are actually asking about the lower end of the k-range or the upper end. If the question is about the upper end, then, as Robert, said, the answer is simple. More data is better, so long as you are mindful of the size of the signal relative to statistical and systematic noise. As for the lower end, you need to remember that the background removal algorithm uses a rather simple-minded, Fourier analysis to distinguish background from XAFS signal. In the region close to the edge -- where the data are changing most rapidly -- the spline probably does not have the freedom to approximate the background function well. Thus, the extracted chi(k) are quite a bit more unreliable below 2 or 3 inv. Ang. than they are at higher k. This may sound like a horrible problem for EXAFS analysis, except that the theory is also unrelible at low k. When the photoelectron has low kinetic energy (i.e. just above the edge), it is very sensitive to the details of the potential surface. Given that Feff uses spherical muffin tins and that spherical muffin tins are a pretty crude approximation, the theory is unreliable below 2 or 3 inv. Ang. Happily, about 2 or 3 inverse Angstroms, both the theory and the extracted data are pretty reliable, which is why EXAFS analysis works. The default kmin in Artemis is 3. You should choose kmax to be as big as possible without extending into a regime where the signal is dominated by statistical or systematic noise. (Section 5.9.1 in Scott's book is helpful in that regard.) HTH, B On 06/18/2015 12:33 PM, Robert Gordon wrote:

Hi Navneet,

You have asked a rather open-ended question. There are numerable resources available for learning about XAFS analysis that are straightforward to find. Setting the k-range is more specific and governed by several factors.

The range chosen affects resolution and precision. In general, you would like as large a k-range as you can reasonably obtain. Practically, this is limited by the sample (order/disorder, mean-square- relative-displacement, Debye-Waller term) and by finite limits on beamtime.

My suggestion, as a starting point, is to consider what type of materials you plan on studying, then check the literature for similar systems to see what results others have been able to obtain.

-R.

On 6/18/2015 3:42 AM, Navneet Singh wrote:

...

Dear All

Can I get some study material mentioning how to set the K-range for EXAFS analysis.

With best regards

Navneet Singh

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