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#1 2024-03-04 17:36:58
- brunosamp
- Member
- Registered: 2023-04-21
- Posts: 18
Question about comparasion in electron-hole analysis
I have 4 coronene structures. One is only the coronene, and the other 3 are functionalized with: Only an OH groups (Cor-OH); Only an epoxy group (Cor-ep), and only a -COOH group (Cor-cooh).
I want to do a electron-hole analysis to characterize the td-dft absorption bands i obtained (If it's n - > pi*, pi -> pi*).
However, i'd also like to compare how the functional group affects the fluorescence of this structure.
To do so, i wanted to compare the charge density difference isosurfaces, to show the localization of electron and hole, and also the Dindex and transition dipole moment.
My question is: In the Cor-OH groups, the highest oscillator strength is in the S9 excitation, in the Cor-Ep is in the S12 and the Cor-COOH is the S11 excitation. I compared them, and all of them are LE excitations. Can i compare the transition dipole moments and the Dindex to try to compare which structure would have a greater emission in the fluorescence spectra?
Or do i have to pick the same excitation (Ex: The S1 excitation of all structures) to properly compare them? The S1 excitation i obtained for them are not observed experimentally, which is why i'm not using it.
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#2 2024-03-05 02:46:01
Re: Question about comparasion in electron-hole analysis
According to Kasha's rule, fluorescence of most molecules (except for very few anti-Kasha molecules, see Chem. Rev. 2017, 117, 13353-13381 and Chem. Rev. 2012, 112, 4541−4568 for reviews) corresponds to emission from S1. It is very common that S1 has a very small or negligible oscillator strength; despite of this, after considering vibronic effect, and/or after long enough time, the emission from S1 is still viable. Before emission from S1, there is usually long enough time to occur sufficient interconversions from high-lying excited states to S1. So, unless you can demonstrate that your molecule doesn't satisfy Kasha's rule, S1 should always be analyzed by Multiwfn to study nature of fluorescence.
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#3 2024-03-05 13:59:59
- brunosamp
- Member
- Registered: 2023-04-21
- Posts: 18
Re: Question about comparasion in electron-hole analysis
I understand now, thank you!
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#4 2024-03-10 16:00:19
- brunosamp
- Member
- Registered: 2023-04-21
- Posts: 18
Re: Question about comparasion in electron-hole analysis
Mr. tian lu, just one last question. Epoxy groups are known to induce non-radiative recombinations. Electron-hole analysis can show this type of behavior?
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