global chi2
Dear Rietvelders I am trying to refine (fullprof) x-ray (Cu Ka) pattern of spinel CuTi2(S,Se)4 which wasmeasured in flat specimen sample holder in D8 Th:Th without monochromator (10-158 2Th). the experiment details were step each 0.02 2Th with 10 sec per step. the background was subtructed in EVA. the problem that i am facing isthatthe R_Bragg is 3.71 but the global chi2 is 7.5 only if i am excluded the region to 10 - 80 2Th. what can be the reason for that? Thank's in advance for your ideas Eli
RE: global chi2
maybe you shouldn't substract the background in EVA, as the model used to simulate it is poor. A better way of taking care of the background may to use some polynomialmodel (for instance)in fullprof, and to refine paramaters of the choosen model. Gilbert TRILLON -Message d'origine-De: eli [mailto:[EMAIL PROTECTED]Envoy: jeudi 26 aot 2004 10:54: [EMAIL PROTECTED]Objet: global chi2 Dear Rietvelders I am trying to refine (fullprof) x-ray (Cu Ka) pattern of spinel CuTi2(S,Se)4 which wasmeasured in flat specimen sample holder in D8 Th:Th without monochromator (10-158 2Th). the experiment details were step each 0.02 2Th with 10 sec per step. the background was subtructed in EVA. the problem that i am facing isthatthe R_Bragg is 3.71 but the global chi2 is 7.5 only if i am excluded the region to 10 - 80 2Th. what can be the reason for that? Thank's in advance for your ideas Eli
Conversion software available?
Dear all I am looking for software that can convert the x-ray diffraction data of one radiation source to the other. Example: I have a diffraction data of Co (1.78897 A) target and I need to convert this to Cu Ka (1.54051 A)for further processiong and comparison. I would highly appreciate if someone can let me know if any such downloadable available. Thanks in advance, Selva * This email is virus free by TrendMicro Inter Scan Security Suite. *
Re: Conversion software available?
WinPlotr, which is can be downloaded at www.ccp14.ac.uk, can do wavelength conversion. Read in your data and choose 'Change wavelength' in the 'X space ' menu. The converted data will be plotted along with your original data. To save the converted data to a file, choose 'save data as multicolumn file' from the 'File' menu. The data will not be saved with constant step length, but this can be achieved by interpolation in e.g. Origin or Excel. The simplest thing to do if you just want to visually compare two data sets at different wavelenghts, is to open them both in WinPlotr and plot them in e.g. Q-space (use the 'X-space' menu again). Regards, Magnus H. Sorby
Re: Conversion software available?
This can also be done with the CMPR program (see CCP14 site or link below). CMPR runs in Windows, OS X and unix. Note that you think carfully about how you would process data after wavelength conversion, as many computations will not give correct results. As one example, anomolous dispersion (f' f) will not be computed correctly. Brian I am looking for software that can convert the x-ray diffraction data of one radiation source to the other. Brian H. Toby, Ph.D.Leader, Crystallography Team [EMAIL PROTECTED] NIST Center for Neutron Research, Stop 8563 voice: 301-975-4297 National Institute of Standards Technology FAX: 301-921-9847Gaithersburg, MD 20899-8563 http://www.ncnr.nist.gov/xtal
