When a d-d complex is used for instance, you need to use the Tanabe-Sugano diagram to predict the transitions permitted by spin mechanism, and Tanabe-Sugano diagram utilize symmetry irreps to represent the energy states. For f-f transitions the irreps are used because forced electric dipole transitions depends on the matrix elements of i-th rank
@@leonardofigueiredo57 what is a Tanabe Sugano diagram? What is forced electric dipole transitions? Which matrix? Can you explain with layman chemist terms? That would be great :)
@@theophilegaudin2329 When a transition metal is inserted in a chemical environment, there's splitting of d orbitals and degenerescence is broken. Therefore, there's an energy gap between the new states due the splitting. This energy gap can be quantized by the Tanabe-Sugano diagram, and this diagram uses irreps to denote the states. UV-Vis spectra of metal transitions complexes (d-d transitions) displays the transitions whose occurrence is due the energy gap between the new states, thus, the irreps are used to assign the bands in UV-Vis spectra. Forced electric dipole mechanism is the mixture between wavefunctions of different parity, which relaxes Laporte selection rule, and symmetry selection rule that says the direct symmetry product must contain the most symmetrical representation (A1g). In lanthanides, the intensity of f-f bands are explained by the forced eletric dipole mechanism. Because of the mixture of wavefunctions, it depends on the tensor matrix elements. The contrary of magnetic dipole transitions, that does not contain the tensor matrix elements, and therefore are independent of the chemical environment.
@@leonardofigueiredo57 How does it use irreps to denote the states? What is different with and without irreps? Let's say a molecule has a single irrep, ie no symmetry at all, and another virtual molecule is exactly identical but has two irreps, what difference does it make on the diagram? What do you mean by wave functions of different parity? What is Laporte selection rule? What is a symmetry product? What tensor are you referring to? Sorry for bombarding questions. Dude, I do have a Ph. D. in comp chem but I don't understand a word of what you are saying here. I am of a different specialty (solvation, thermodynamics, electrostatics). I'm sure you can find a way to explain this to me that is accessible to me.
Behind group theory, it was proved by abstract algebra and linear algebra that are hard to understand for chemist. The great orthogonal theorem is a concept to get irreps. And irreps relate to algebraic wave function of electron in quantum mechanics.
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how does she write that?
Super helpful! Thank you
Why do we need irreps to understand the prediction of UV/Vis spectra?
When a d-d complex is used for instance, you need to use the Tanabe-Sugano diagram to predict the transitions permitted by spin mechanism, and Tanabe-Sugano diagram utilize symmetry irreps to represent the energy states. For f-f transitions the irreps are used because forced electric dipole transitions depends on the matrix elements of i-th rank
@@leonardofigueiredo57 what is a Tanabe Sugano diagram?
What is forced electric dipole transitions?
Which matrix?
Can you explain with layman chemist terms?
That would be great :)
@@theophilegaudin2329 When a transition metal is inserted in a chemical environment, there's splitting of d orbitals and degenerescence is broken. Therefore, there's an energy gap between the new states due the splitting. This energy gap can be quantized by the Tanabe-Sugano diagram, and this diagram uses irreps to denote the states. UV-Vis spectra of metal transitions complexes (d-d transitions) displays the transitions whose occurrence is due the energy gap between the new states, thus, the irreps are used to assign the bands in UV-Vis spectra.
Forced electric dipole mechanism is the mixture between wavefunctions of different parity, which relaxes Laporte selection rule, and symmetry selection rule that says the direct symmetry product must contain the most symmetrical representation (A1g). In lanthanides, the intensity of f-f bands are explained by the forced eletric dipole mechanism. Because of the mixture of wavefunctions, it depends on the tensor matrix elements. The contrary of magnetic dipole transitions, that does not contain the tensor matrix elements, and therefore are independent of the chemical environment.
@@leonardofigueiredo57 How does it use irreps to denote the states? What is different with and without irreps? Let's say a molecule has a single irrep, ie no symmetry at all, and another virtual molecule is exactly identical but has two irreps, what difference does it make on the diagram?
What do you mean by wave functions of different parity? What is Laporte selection rule? What is a symmetry product? What tensor are you referring to?
Sorry for bombarding questions. Dude, I do have a Ph. D. in comp chem but I don't understand a word of what you are saying here. I am of a different specialty (solvation, thermodynamics, electrostatics). I'm sure you can find a way to explain this to me that is accessible to me.
Behind group theory, it was proved by abstract algebra and linear algebra that are hard to understand for chemist.
The great orthogonal theorem is a concept to get irreps.
And irreps relate to algebraic wave function of electron in quantum mechanics.
excellent!