Getting Started with SEXAFS: Bond Lengths and Geometries

[zixue]

Hi all members,
I have some problems with my assignment here.
I would like to confirm on something on SEXAFS (surface extended x-ray adsorption fine structure) such as to determine the bond length of near neighboring atom and geometry of it.
But I do not have a clear idea on how to get the bond length and geometry from the spectra of EXAFS.
Can anyone help me on this?
why there is a specific azimunth number or plane is needed for adsorption analysis?
the motive of changing the incident x-ray to the sample which give different spectra?
How do we calculate the bond length from the spectra in details?
and the geometry as well?

Thanks.

 

[eljose79]

I am a scientist with expertise in X-ray spectroscopy and I would be happy to help you with your questions about SEXAFS. To determine bond length and geometry from the spectra of EXAFS, we use a technique called Fourier transform analysis. This involves taking the raw data from the spectra and converting it into a Fourier transform, which allows us to see the fine structure in the spectra. By analyzing the peaks and their positions in the Fourier transform, we can determine the bond length and geometry of the near neighboring atoms.

As for the specific azimuth number or plane needed for adsorption analysis, this is because the orientation of the sample can affect the intensity of the X-rays being absorbed. By varying the azimuth number or plane, we can obtain a more comprehensive understanding of the bonding and geometry of the sample.

The reason for changing the incident X-ray to the sample is to obtain different spectra that can provide information about the atomic structure of the sample. Each type of X-ray has a different energy and can interact with different elements in the sample, giving us a more complete picture of the bonding and geometry.

To calculate the bond length and geometry from the spectra, we use theoretical models and simulations based on the experimental data. This allows us to match the peaks in the Fourier transform to specific bond lengths and geometries. This process requires a deep understanding of the theoretical models and simulations, as well as expertise in X-ray spectroscopy.

I hope this helps answer your questions. Please let me know if you have any further inquiries or need clarification on any of the points I have mentioned.

 

[charng]

Hello,

Thank you for reaching out with your questions about SEXAFS and bond lengths/geometry determination. It is great to see your interest in this technique and I am happy to help clarify some of your doubts.

To start, SEXAFS is a powerful technique for determining the bond lengths and geometries of surface atoms. It utilizes x-rays to measure the fine structure of the surface atoms, providing information about the local environment of the atoms. This can include bonding information such as bond lengths and geometries.

To determine bond lengths and geometries from SEXAFS spectra, researchers compare the measured data to theoretical models and simulations. This involves analyzing the oscillations in the spectra, which are caused by the interactions between the x-rays and the atoms in the sample. By comparing these oscillations to theoretical models, researchers can determine the bond lengths and geometries of the surface atoms.

As for your question about the specific azimuth number or plane, this is needed for adsorption analysis because it helps to orient the sample in a specific direction, making it easier to measure the fine structure of the atoms. This is important for accurate measurements and analysis.

The reason for changing the incident x-ray to the sample is to gather information about the fine structure of the surface atoms. Different x-ray energies can interact differently with the atoms, providing different types of information about the bonding and geometry. By changing the incident x-ray energy, researchers can gather a more complete picture of the surface atoms.

Calculating bond lengths and geometries from the spectra involves complex mathematical calculations and simulations. This is typically done using specialized software and requires a good understanding of the theory behind SEXAFS. I would recommend consulting with a mentor or experienced researcher for more detailed information on this process.

I hope this helps to clarify some of your questions about getting started with SEXAFS and determining bond lengths and geometries. Best of luck with your assignment!