Split white line in TcO2 spectra and similar Tc(IV) octahedral environments
Hi, Tc(IV) which is a d3 configuration ion, when octahedrally coordinated by O ligands eg TcO2 has what I would call a split white line (see attached image) in the K-edge XANEs. Others might call it a very strong second resonance . The image is from TC in an iron oxide phase by the way. One of my collaborators asked me why does the edge have two peaks.? This is a simple question but is there a simple answer? In a literature search although the shape seems accepted I couldn't find a straightforward explanation. Ce(IV) L3 spectra have a split white line due to some sort of crystal field effect but there the transition (L3-edge) is direct to d states so it's a bit more obvious. Here it's an s-p transition formally so you'd think it must be some sort of split p state explanation , but I am not sure why? I am sure you could XANES simulate this to reproduce it but that doesn't answer the question why in simple terms. It may be it 's a complicated band structure explanation and so there is no simple answer but if anyone has read or knows one , I 'd be interested,. There are some similar effects in the white lines of Zr K-edge spectra , when the Zr is also octahedral but I can only find reports of that not the reason for it. BTW This is definitely pure Tc(IV) so the answer is not multiple oxidation states., which has been used to explain different Tc split white lines in other situations. Thanks Fred Prof. J F W Mosselmans Principal Beamline Scientist I18 Diamond Light Source Diamond House Harwell Campus Didcot Oxon OX11 ODE UK T 00 44 1235 778568 M 00 44 7785510211 E fred.mosselmans@diamond.ac.uk F 00 44 1235 778448 Never mind the W it's the tax that counts -- This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom
Hi Fred,
The second resonance is due to scattering, mainly the multiple scattering
path involving the trans oxygen ligands of the octahedral Tc coordination
sphere, I believe. In other words, it is the beginning of the EXAFS
spectrum. These features are particularly prominent for Tc.
This is the characteristic XANES spectrum of Tc(IV) in an octahedral
environment with O neighbors.
Sincerely,
Wayne
ps If you look at the theoretical scattering curves from Feff, you can
identify which scattering path is responsible for this peak. If I recall
correctly, it is the path that I mentioned, but I may misremember.
On Mon, Aug 5, 2013 at 11:40 PM,
Hi,****
** **
Tc(IV) which is a d3 configuration ion, when octahedrally coordinated by O ligands eg TcO2 has what I would call a split white line (see attached image) in the K-edge XANEs. Others might call it a very strong second resonance . The image is from TC in an iron oxide phase by the way.****
One of my collaborators asked me why does the edge have two peaks.?****
This is a simple question but is there a simple answer? In a literature search although the shape seems accepted I couldn’t find a straightforward explanation.****
Ce(IV) L3 spectra have a split white line due to some sort of crystal field effect but there the transition (L3-edge) is direct to d states so it’s a bit more obvious. Here it’s an s-p transition formally so you’d think it must be some sort of split p state explanation , but I am not sure why?****
I am sure you could XANES simulate this to reproduce it but that doesn’t answer the question why in simple terms. It may be it ‘s a complicated band structure explanation and so there is no simple answer but if anyone has read or knows one , I ‘d be interested,.****
There are some similar effects in the white lines of Zr K-edge spectra , when the Zr is also octahedral but I can only find reports of that not the reason for it. ****
BTW This is definitely pure Tc(IV) so the answer is not multiple oxidation states., which has been used to explain different Tc split white lines in other situations.****
Thanks****
Fred****
** **
** **
Prof. J F W Mosselmans****
Principal Beamline Scientist I18****
Diamond Light Source****
Diamond House****
Harwell Campus****
Didcot****
Oxon****
OX11 ODE****
UK****
** **
T 00 44 1235 778568****
M 00 44 7785510211****
E fred.mosselmans@diamond.ac.uk****
F 00 44 1235 778448****
** **
Never mind the W it's the tax that counts****
** **
--
This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom
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-- Wayne Lukens Staff Scientist Lawrence Berkeley National Lab
Hi Fred, If you want to get a simple answer, first, try to calculate XANES in TcO_6 octahedron only. If you reproduce the split the simple answer does exist though it may be not obvious. If the split is not reproduced in 7- atomic cluster the situation is worse. Try to increase the cluster and see what will happen. I am not sure that EXAFS approximation works sufficiently well for this energy region. Regards. Victor Krayzman MML. NIST. Gaithersburg Hi, Tc(IV) which is a d3 configuration ion, when octahedrally coordinated by O ligands eg TcO2 has what I would call a split white line (see attached image) in the K-edge XANEs. Others might call it a very strong second resonance . The image is from TC in an iron oxide phase by the way. One of my collaborators asked me why does the edge have two peaks.? This is a simple question but is there a simple answer? In a literature search although the shape seems accepted I couldn’t find a straightforward explanation. Ce(IV) L3 spectra have a split white line due to some sort of crystal field effect but there the transition (L3-edge) is direct to d states so it’s a bit more obvious. Here it’s an s-p transition formally so you’d think it must be some sort of split p state explanation , but I am not sure why? I am sure you could XANES simulate this to reproduce it but that doesn’t answer the question why in simple terms. It may be it ‘s a complicated band structure explanation and so there is no simple answer but if anyone has read or knows one , I ‘d be interested,. There are some similar effects in the white lines of Zr K-edge spectra , when the Zr is also octahedral but I can only find reports of that not the reason for it. BTW This is definitely pure Tc(IV) so the answer is not multiple oxidation states., which has been used to explain different Tc split white lines in other situations. Thanks Fred Prof. J F W Mosselmans Principal Beamline Scientist I18 Diamond Light Source Diamond House Harwell Campus Didcot Oxon OX11 ODE UK T 00 44 1235 778568 M 00 44 7785510211 E fred.mosselmans@diamond.ac.uk F 00 44 1235 778448 Never mind the W it's the tax that counts -- This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
participants (3)
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fred.mosselmans＠diamond.ac.uk -
vikrai＠comcast.net -
Wayne Lukens