Why Do Sulfurous Compounds Show Different Peaks in X-ray Absorption Spectra?

  • #1
feelice
1
0
Homework Statement
Interpretation of X-ray absorption spectra
Relevant Equations
none
Hey guys :)

actually my homework was just to research the absorption spectra of some iron compounds and some sulfurus compounds - to which I have the answer. I just dont understand it. In this arcticle, fig 2b: "Phase Composition of Iron Oxide Nanoparticles Studied Using Hard X-ray Absorption Spectroscopy" the needed FeO, hematite and magnetite are listet. It was explained to the course, that roughly the oxidation state is added to the shift of the Fe-K-absorption edge which fits, also that tetrahedral conformation will lead to a pre peak, which also fits.
Now we come to the sulfurous compounds. In this article, fig.3b: "In Situ Analysis of Sulfur Species in Sulfur Globules Produced from Thiosulfate by Thermoanaerobacter sulfurigignens and Thermoanaerobacterium thermosulfurigenes", the sodium thiosulfate is somehow not fitting in for me. Why does ist have two main peaks - if you say because on sulfur has the oxidation state -1 and the other plus 5, then why does magnetite only have on peak even though it has one iron in oxidation stat +2 and the other two in +3. Why do we split in thiosulfate?

It really bothers me and I would be very glad if someone could help me solve this puzzle.
 
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  • #2
feelice said:
Homework Statement: Interpretation of X-ray absorption spectra
Relevant Equations: none

In this arcticle, fig 2b:

do you have links to the 2 articles you are reading, please
 

FAQ: Why Do Sulfurous Compounds Show Different Peaks in X-ray Absorption Spectra?

Why do sulfurous compounds show different peaks in X-ray absorption spectra?

Sulfurous compounds show different peaks in X-ray absorption spectra due to variations in their electronic structure and chemical environment. The differences in oxidation states, coordination chemistry, and bonding can lead to distinct absorption features, as the energy required to excite core electrons to unoccupied states varies.

How does the oxidation state of sulfur affect its X-ray absorption spectra?

The oxidation state of sulfur significantly affects its X-ray absorption spectra because it alters the electron density around the sulfur atom. Higher oxidation states typically result in higher energy absorption edges due to the increased effective nuclear charge experienced by the core electrons, leading to shifts in peak positions.

What role does the chemical environment play in the X-ray absorption spectra of sulfurous compounds?

The chemical environment, including the types of atoms bonded to sulfur and the overall molecular structure, influences the X-ray absorption spectra. Different surrounding atoms can cause variations in electron distribution and local symmetry, leading to changes in absorption peak positions and intensities.

Can coordination geometry influence the X-ray absorption spectra of sulfur compounds?

Yes, coordination geometry can influence the X-ray absorption spectra of sulfur compounds. Different geometries, such as tetrahedral or octahedral arrangements, affect the local electronic structure and symmetry, which in turn alters the energy levels and transition probabilities, resulting in distinct spectral features.

How do bonding characteristics affect the X-ray absorption spectra of sulfurous compounds?

Bonding characteristics, such as bond length, bond angle, and the nature of the chemical bonds (ionic, covalent, etc.), affect the X-ray absorption spectra. These factors influence the electronic states available for transitions and the energy required for these transitions, leading to variations in the absorption peaks.

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