February 2024 - Ifeffit - millenia.cars.aps.anl.gov

weak scattering from second-nearest neighbors for single atom catalysts
by Qiang 08 Feb '24

08 Feb '24

Hi everyone, I would like to have a discussion about the common EXAFS for single atom catalysts. It is usually observed that there is only one strong peak around 1.5A in EXAFS, and it is attributed to the nearest neighbors of O or N. Take an example of Pt1/CeO2 catalyst. Pt single atom is coordinated with a few oxygens, i.e., PtOx. These oxygens constitute the first shell of Pt. It is supposed that these O should also attach to the metal element of the support (Ce here). So there is also Pt-O-Ce structure. Why it doesnot have strong scattering peak in EXAFS? Is it that because the Pt-O-Ce formed is not ordered, or it is actually not a bond just some weak contact? Thank you very much. Qiang

3 2

Larch version up problem
by 정은석 07 Feb '24

07 Feb '24

Hello~ I used Larch 0.9.71. until now. However, I would like to update larch and I reinstall anaconda and larch. I installed Larch 0.9.74. as following installation guide I didn't have any problems during the installation process. However, I faced problems during feffit fitting. Before, I used feffit fitting in larch 0.9.71., and then I hadn't had any problems. I only changed larch as new version. What am I doing? When I run feffit fitting, I have debugs as the below: ------------------------------------------------------------------------------------------------------------------------- File "c:\Users\Administrator\Desktop\RL\feffit_error_test\test-feffit.py", line 51, in <module> out = feffit(pars, dset) ^^^^^^^^^^^^^^^^^^ File "C:\ProgramData\anaconda3\envs\xraylarch\Lib\site-packages\larch\xafs\feffit.py", line 645, in feffit ds.prepare_fit(params=params, other_hashkeys=dset_hashkeys) File "C:\ProgramData\anaconda3\envs\xraylarch\Lib\site-packages\larch\xafs\feffit.py", line 374, in prepare_fit self._generate_hashkey(other_hashkeys=other_hashkeys) File "C:\ProgramData\anaconda3\envs\xraylarch\Lib\site-packages\larch\xafs\feffit.py", line 291, in _generate_hashkey dat = [self.data.ek0, self.data.e0, self.data.rbkg] ^^^^^^^^^^^^^ AttributeError: 'Group' object has no attribute 'ek0' ---------------------------------------------------------------------------------------------------------------------- -- Best regards, Ph. D. Eun-Suk Jeong X-ray absorption fine structure(EXAFS+XANES) Mobile:+82-10-4628-9896

2 8

Larch version up problem in Python, Window 10
by 정은석 03 Feb '24

03 Feb '24

Hello~ I have used Larch 0.9.71. until now. However, I would like to update larch and I reinstall anaconda and larch. I installed Larch 0.9.74. as following installation guide I didn't have any problems during the installation process. However, I faced problems during feffit fitting. Before, I used feffit fitting in larch 0.9.71., and then I hadn't had any problems. I changed larch as new version. What am I doing? When I run feffit fitting in python, I have debugs as the below: ------------------------------------------------------------------------------------------------------------------------- File "c:\Users\Administrator\Desktop\RL\feffit_error_test\test-feffit.py", line 51, in <module> out = feffit(pars, dset) ^^^^^^^^^^^^^^^^^^ File "C:\ProgramData\anaconda3\envs\xraylarch\Lib\site-packages\larch\xafs\feffit.py", line 645, in feffit ds.prepare_fit(params=params, other_hashkeys=dset_hashkeys) File "C:\ProgramData\anaconda3\envs\xraylarch\Lib\site-packages\larch\xafs\feffit.py", line 374, in prepare_fit self._generate_hashkey(other_hashkeys=other_hashkeys) File "C:\ProgramData\anaconda3\envs\xraylarch\Lib\site-packages\larch\xafs\feffit.py", line 291, in _generate_hashkey dat = [self.data.ek0, self.data.e0, self.data.rbkg] ^^^^^^^^^^^^^ AttributeError: 'Group' object has no attribute 'ek0' ---------------------------------------------------------------------------------------------------------------------- The data(EXAFS(k)), which are inputted for feffit, have two column, k and chi. As you know, it doesn't have ek0. -- Best regards, Ph. D. Eun-Suk Jeong X-ray absorption fine structure(EXAFS+XANES) Mobile:+82-10-4628-9896

1 0