Photoinduced Electron Transfer - The Classical Marcus Theory, René M. Williams, UvA
Вставка
- Опубліковано 28 гру 2024
- #theory #chemistry #education #photochemistry #marcus #molecular #chargetransfer #electrontransfer
This is a recorded Zoom lecture at the MSc level for chemistry students that are interested in molecular photochemistry. It discusses the different aspects that play a role in the so-called Classical Marcus theory of electron transfer. Next to the Gibbs Free energy, also the reorganization energy and the electronic coupling are presented. In the last part the Franck Condon Weighted Density of States in the Semi-classical Marcus Inverted Region also features. Learning objectives:
• Photochemistry has a direct link with quantum chemistry.
• Intermolecular (or inter-chromophoric) interactions in the excited state can lead to electronic interactions enabling transfer processes.
NEW ADDITION: 15-05-2024
For some mathematical modules on these topics that are freely available see:
demonstrations...
(you need the free Wolfram Player, than you can use it).
NOTE:
A good description of the (summation factor in the) Semi-Classical Marcus equation can be found here:
doi.org/10.102... (Links to an external site.)
Quoted from there:
"This rather complex looking expression can be fairly easily understood. The terms in front of the Franck−Condon (FC) factor are the frequency of electron transfer in the absence of a barrier; this contains V and the classical density of states. The Franck−Condon factor itself consists of the sum over all possible vibrational overlap integrals between the initial vibrational level v and the final level m. Each individual m represents a separate v = 0 → m reaction channel. Each separate exponential term in the sum is the population of molecules in the assembly having the required energy to undergo electron transfer with energy conservation through channel v = 0 → m. The sum is dominated by channels for which |ΔG0| ∼ λ0 + mℏω, so there is a close energy match between the energy released (ΔG0) and the sum of the reorganization energy and the initial product vibrational energy (mℏω)."
So it is not the exact vibrational quantum number, but it are the reaction channels related to individual vibrational levels.
CORRECTION 23-03-2021:
In practice, you can take m = 0 to m = 15.
For m = 0 this equation is NOT zero. (it looks like a Classical Marcus curve).
After m = 15 contributions become negligible.
For more information see:
Electron Transfer Reactions in Chemistry: Theory and Experiment (Nobel Lecture)†
Prof. Dr. Rudolph A. Marcus
doi.org/10.100...
Electron Transfer Assisted by Vibronic Coupling from Multiple Modes,
(the nice pictures of vibronic coupling in inverted region)
doi.org/10.102...
Contemporary Issues in Electron Transfer Research
doi.org/10.102...
Jacques E. Moser:
photochemistry....
Introduction to Electron Transfer, René M Williams
doi.org/10.131...
Thanks to Prof. Dr. A.M. Brouwer for some of his slides!!
Thanks to Yorrick Boeije, Heleen Groenewegen, Isa Awad and Said Ortega for asking questions!!
ADDITION 2-11-2021:
For some recent review work on this topic see:
Introduction to Electron Transfer: Theoretical Foundations and Pedagogical Examples
Eric J. Piechota and Gerald J. Meyer
doi.org/10.102...
Introduction to Marcus Theory of Electron Transfer Reactions
Francesco Di Giacomo
doi.org/10.114...
Multifaceted aspects of charge transfer
Valentine I. Vullev et al.
doi.org/10.103...
Derivation of Marcus equation:
www.int.washing...
Thanks so much for uploading this! It's very clear and easy for a beginner, like myself, to follow.
Glad to hear that!
Cheers!
The dielectric constant effect can interpret using Frenkel binding energy effect. If it increases usually the separation must be higher
Yes indeed, we have studied temperature effects on charge separation, correcting for changes of dielectric constants! doi.org/10.1021/jp0372688.
This can be incorporated into (Semi-)Classical Marcus.
How Marcus free energy relation with the binding energy and thermal influence to dealing as thermodynamics perspective for electron transfer from organics molecular materials by light absorption?
A lecture about the temperature dependence of electron transfer is indeed a very good suggestion!! For the natural photosynthetic reaction center it is pretty complex. I might give it a try.
Does delocalization decrease or increase with the binding and temperature effect? How driving force or free energy is varied with both effects? Could you please explain a bit?
One important effect of temperature on the driving force is through the increase of the dielectric constant of the medium.
Sir, will you please provide full derivation of rate constant defined by Marcus Theory?
Try this one:
www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjJ35qrhePxAhVHP-wKHdJOBl4QFnoECAIQAA&url=http%3A%2F%2Fwww.int.washington.edu%2Fusers%2Fbertsch%2Fmarcus.1.pdf&usg=AOvVaw2LpkGvYHjaWso3qSdqsw8A
what was the software that was used to determine those parameters
The interactive graphs in this video were made with Mathematica modules, that are now freely available at Wolfram: demonstrations.wolfram.com/author.html?author=Ren%C3%A9%20M.%20Williams
They are intended as useful tools to easily apply the theory.
Thumbnail at 54:00
Very informative video. Sir i want to know about charge transfer in porphyrin ring system. But i don't know where I can find the relevant material. Could you please suggest any reference or article? It would be very helpful. Thankyou. From 🇮🇳
Hi,
Here are two papers on porphyrin and electron transfer:
pubs.acs.org/doi/10.1021/ja038676s
pubs.acs.org/doi/10.1021/ja992127y
And one on pi extended porphs:
doi.org/10.1002/chem.201905372
And one on using porphyrins as sensitizer for water oxidation:
doi.org/10.1039/C4EE03302G
Success
Sir can you give me any paper which can give enough knowledge about proton coupled electron transfer?
... I will have a look...see what I can find.
How about:
www.annualreviews.org/doi/abs/10.1146/annurev.biochem.78.080207.092132
doi.org/10.1021/cr0500030
Thank you sir .