Re: [Ifeffit] Ifeffit Digest, Vol 93, Issue 16

2010-11-22 Thread Jatinkumar Rana
On 21.11.2010 19:00, ifeffit-requ...@millenia.cars.aps.anl.gov wrote: Send Ifeffit mailing list submissions to ifeffit@millenia.cars.aps.anl.gov To subscribe or unsubscribe via the World Wide Web, visit http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit or, via email,

Re: [Ifeffit] Transmission EXAFS sample

2010-11-22 Thread Welter, Edmund
Dear Jatin, the optimum mued of 2.x is not just derived by simple photon counting statistics. As Matt pointed out, for transmission measurements at a synchrotron beamline in conventional scanning mode this is seldom a matter. Nevertheless, one should avoid to measure subtle changes of

Re: [Ifeffit] Transmission EXAFS sample

2010-11-22 Thread Jatinkumar Rana
On 21.11.2010 19:00, ifeffit-requ...@millenia.cars.aps.anl.gov wrote: Send Ifeffit mailing list submissions to ifeffit@millenia.cars.aps.anl.gov To subscribe or unsubscribe via the World Wide Web, visit http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit or, via email,

Re: [Ifeffit] Transmission EXAFS sample

2010-11-22 Thread Scott Calvin
On Nov 22, 2010, at 7:09 AM, Jatinkumar Rana wrote: Hi Scott, Sorry for mixing up the things. For the case, when i have very limited amount of sample that i can not cover 1sq.cm area, you, Matt and others have given very very clear explanation about possible solutions and the probable

[Ifeffit] Distortion of transmission spectra due to particle size

2010-11-22 Thread Scott Calvin
Hi all, I'm tracking down a piece of EXAFS lore which I think is incorrect. I've seen it said that you cannot compensate for the distortion introduced by large particle sizes by making the sample thicker. Certainly thick samples have their own set of issues (e.g. thickness effects from

Re: [Ifeffit] Distortion of transmission spectra due to particle size

2010-11-22 Thread Matthew Marcus
I think there is a confusion over what is being averaged. As an example, consider a layer of particles which are completely opaque, and let's say that the area fraction is 1/2. If the particles lined up, then the transmission would be 1/2 for any N, whereas if the layers were random, then

Re: [Ifeffit] Distortion of transmission spectra due to particlesize

2010-11-22 Thread Ravel, Bruce
I think you are correct in principle that more layers can reduce the thickness effect problem. If harmonics were not an issue, eventually if you pile up enough random layers, the thickness will be uniform. Whether this is useful in practice is another matter, but suspect it may not be when

Re: [Ifeffit] Distortion of transmission spectra due to particle size

2010-11-22 Thread Matt Newville
Scott, I agree with Jeremy and Matthew. Layering very small (compared to an absorption length) spheres is exactly what powder on tape and mixing with a low-Z binder do, and that's why these are the preferred methods for turning a powder into a sample of uniform thickness. If the spheres are not

Re: [Ifeffit] Distortion of transmission spectra due to particle size

2010-11-22 Thread Matt Newville
On Mon, Nov 22, 2010 at 4:55 PM, Scott Calvin dr.scott.cal...@gmail.com wrote: Some follow-up. This, for example, is from an excellent workshop presentation by Rob Scarrow: Errors from large particles are independent of thickness Yes... one can have a sample that is uniform, or made of small

Re: [Ifeffit] maximum number of paths in Artemis

2010-11-22 Thread Matt Newville
Hi Yuan, Bruce, It looks like I need to make a dll with more than 512 paths. I'm on this, but it might take me a day or so. --Matt On Mon, Nov 22, 2010 at 5:09 PM, Bruce Ravel bra...@bnl.gov wrote: Yuan, It seems unwise to post a new question at the end of a long and active thread.  

Re: [Ifeffit] maximum number of paths in Artemis

2010-11-22 Thread Matt Newville
Yuan, All, I put several Windows dlls for Ifeffit at http://cars9.uchicago.edu/~ifeffit/src/Win32_dlls/1.2.12/ There are versions there with 256, 512, 1024, and 2048 paths.I have not tested these beyond loading them, and running a trivial python script. Please let me know if there are