All Questions
Tagged with symmetry spectroscopy
21
questions
2
votes
0
answers
133
views
Deduce the shapes of stretching modes of a tetrahedral molecule
This question is in relation to the [FeCl4]- molecule, which is tetrahedral. I previously deduced, using symmetry analysis, that the vectors corresponding to the bonds of the molecule will be A1+T2, ...
2
votes
1
answer
208
views
Is there a difference between $A_{1g}$ modes and $A_{g}$ modes?
I know that both are totally symmetric and that the '$1$', according to the Mulliken table, refers to symmetry around the $C_2$ axis but I was reading some papers and found that modes were sometimes ...
- 65
3
votes
1
answer
50
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Are A1g modes reduced at 180 degrees polarisation in Raman spectra?
I have read that A1g modes are identifiable in Raman spectra by looking at cross-polarised Raman spectra and seeing peaks that strongly reduce in intensity. So essentially, the intensity of A1g modes ...
- 65
2
votes
0
answers
77
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Factor Group Analysis of Na2SO4 - Site Group Symmetry
I'm still trying to understand how to construct a factor group analysis for a given molecular point group and the resulting solid state group symmetry. For this I searched for some examples and found ...
- 4,322
10
votes
0
answers
141
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Using symmetry and group theory arguments to explain iron(II) in a tetrahedral crystal field
I am trying to figure out how to explain $1s \rightarrow 3d$ spectroscopic transitions for $\ce{Fe^{2+}}$ in $T_\mathrm{d}$ symmetry. These transitions make up the pre-edge region in K edge X-ray ...
- 101
1
vote
0
answers
48
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electronic transition for polyenic molecules
I am having troubles with polyenes states symmetry.
I found an exercise on the pentadien, where they ask us to analyze the symmetry of the singlet excited states corresponding to:
State S1: π+ →π+
...
- 31
0
votes
0
answers
63
views
Point group specific definition
Does the term only refer to molecules that have the same symmetry elements or exactly the same symmetry operations. Online I see that its the same symmetry operation however my professor's slides show ...
- 748
2
votes
0
answers
249
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Why is the transition (0,0,0) -> (1,0,1) observed in a gas phase IR spectrum of CO2?
Let ($v_1$,$v_2$,$v_3$) denote the vibrational state of $CO_2$.
Why is the transition $(0,0,0)\rightarrow (1,0,1)$ observed when the trasition $(0,0,0)\rightarrow(1,0,0)$ (asymmetric stretch) is not ...
- 21
13
votes
2
answers
2k
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Relationship between the symmetry number of a molecule as used in rotational spectroscopy and point group
While doing a problem set I noticed that the symmetry number of a molecule turns out (usually) to be half the number of symmetry elements that the point group the molecule belongs to.
When I say ...
- 1,443
7
votes
1
answer
423
views
Determining overtones bands of degenerate modes
I have a question of a more mathematical nature on the mathSE (Symmetric Direct Product Distributive?) that received a good answer, but I think an answer more oriented to chemists would be a useful ...
- 11.8k
2
votes
1
answer
635
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D3d point group matrices
I am trying to construct all the matrices for the point group D3d operations. I find that the matrices of E, i, S6, inverse of S6, C3, and inverse of C3 are easy, but I do not know how to construct ...
- 353
6
votes
1
answer
1k
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Rotovibrational selection rules for symmetric tops
The selection rules for symmetric top molecules are
$\Delta J = 0, \pm1$ and $\Delta K = 0$ for $K \neq 0$ (parallel transition)
$\Delta J = \pm1$ and $\Delta K = 0$ for $K = 0$ (parallel ...
- 1,696
1
vote
1
answer
467
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Spectroscopy pyrazine molecule
Considering pyridazine and pyrazine molecules, I am asked to say if I can distinguish one from the other in a sample.
I supposed that is possible because pyrazine belongs to D2h and so it has the ...
- 51
6
votes
2
answers
363
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Potential wells and symmetry in absorption spectroscopy
In a course I am following, we are analyzing the potential wells in molecular absorption spectroscopy.
For molecules with more than one normal mode, we can study the potential wells involved in ...
- 163
8
votes
1
answer
3k
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Determination of +/- reflections in sigma molecular term symbols
This page, which depicts the molecular term symbols for the $\ce{O2}$ and $\ce{O2-}$ (Edit: Mistaken on $\ce{O2-}$) molecules, perhaps best summarizes the full scope of my questions. In general, I don'...
- 1,648