On Saturday 13 May 2006 17:20, Arkadiusz Onyszko wrote:
Dear All, I found in manual, that lamda ~ 1/sqrt(Ei) I want calculate lambda with fitting parameter Ei. How do it ? What is the exact dependence Ei and lambda ? During fitting I have example Ei=7,5, so I want calculate lambda. This dependence: lamda ~ 1/sqrt(Ei) is not a complitly.
When fitting with Ifeffit, Ei is a correction to the broadening terms in Feff, one of which is the mean free path. The exact effect of Ei on the exafs equation as used in Feff and Ifeffit is explained in chapter 6 of this document: http://cars.uchicago.edu/~newville/feffit/feffit.ps Asyou can see from equation 6.2, Ei is actually a correction to the complex momentum. The complex momentum is related to the mean free path, but also to other things in Feff's energy model. This makes the precise interpretation of Ei rather subjective. Is Ei a correction to Feff's loss terms? Is it a correction to Feff's value of the mean free path? Both? Apparently, you are hoping that you can interpret Ei entirely as a correction to the mean free path. I'm not sure how you know that, but if so, Eq. 6.2 tells you how to do so. (And don't forget the constants -- 2m_e/hbar^2!) Hope that helps, B -- Bruce Ravel ---------------------------------------------- bravel@anl.gov Molecular Environmental Science Group, Building 203, Room E-165 MRCAT, Sector 10, Advanced Photon Source, Building 433, Room B007 Argonne National Laboratory phone and voice mail: (1) 630 252 5033 Argonne IL 60439, USA fax: (1) 630 252 9793 My homepage: http://cars9.uchicago.edu/~ravel EXAFS software: http://cars9.uchicago.edu/~ravel/software/