I've synthesized LaFeO3-xNx thin film by magnetron sputtering. The amount of nitrogen is very low (few %at). On FTIR measurements I observe a vibration mode position at around 2000cm-1, that I cannot attribute (vibration mode of the perovskite are situated from 100 to 600cm-1).
This should be due to N=N link, but it has to be link with something to get a IR vibration.
Do you have an idea to see such a vibration by other method (I'm currently doing RAMAN spectra)?
Does anyone already observe similar vibration mode position in nitrogen containing sample?
Thanks
I agree with you that it may be the nitrogen triple bond which in the gas phase should appear around 2360 cm-1 (Raman active) which may be somewhat weakened by e.g. absorption -although absorption on metals does not shift considerably the spectrum:
http://myweb.ncku.edu.tw/~wanghp/Infrared%20spectroscopic%20study%20of%20molecular%20nitrogen%20chemisorption%20on%20rhodium%20surfaces.pdf
but chemisorption may shift the frequency considerably:
http://link.springer.com/article/10.1007%2FBF01575707#page-1
In additio to my previous answer (which did not as yet appear on the website) I would suggest using XPS (ESCA) spectroscopy, as itgives information about the oxidation state of nitrogen involved in the vibration. (Chemical shift and fine resolution analysis of the N1s line). In this frequency range only triple bonds, or cumulated double bonds are active.
Dear Gyorgy,
Thank you for these answer. I plan to do RAMAN first, XPS could be useful as well. However, I think that beam interaction will modify the surface state, and can remove nitrogen. I've already observed these phenomena with EELS: after few second of acquisition, the nitrogen peak disapear.
But, I will try!
Regarding to not having any idea about the materials handling but if it is exposed to air. It may be adsorption/absorption of CO2 on the surface/cavities of your materials? I know the pure CO2 signal is not matching with your data but due to strong interactions between the surface groups, it could be shifted. That's why i would suggest to look for it if there is a chance of interaction.
Best Regards
Thank you for the reply. No the film does not contain pores, and it is dense.
Dear Emile, I am not a practicing XPS spectroscopist, although I have been involved in project, where XPS has been heavily utilized. You should consult a "real" expert. Maybe it is possible to do the test at cryogenic temperature, where desorption is lower. You may also try to do UV-VIS test , as it also tells you something about the state of nitrogen in the sample. N15 NMR in the solid state is also an option. NQR (nitrogen quadrupole resonance) is also possible for N14 isotope. Maybe it is possible to extract information from EXAFS too, but I am not sure.
Hi pls look at this paper ,http://www.hindawi.com/journals/amse/2012/380306/
Dear Faruk,
I've checked the paper that you mentionned, but there is no any vibration at 2000cm-1. We have done some ab initio calculation, and apparently, the mode correspond to N-N stretching. It should be published soon.
Dear all,
Here is the pdf file of the twos articles dealing with experiments and simulation about this new vibration mode.
Regards,
Emile HAYE
Dear All,
As additionnal remarks, we recently published a paper on the compelte infrared signature on REMO3 (LaFeO3, PrFeO3, NdFeO3, SmFeO3, LaCoO3, PrCoO3, NdCoO3 and SmCoO3), from experimental and simulation.
here is the link:
Article Experimental and Theoretical Infrared Signatures of REMO 3 (...
Regards,
Emile HAYE
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