René M. Williams
René M. Williams
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Light Activated Molecular Motors: Rotaxanes and Cis-Trans Isomerization of Feringa Rotors Nobel 2016
#nanomaterials #education #photochemistry #nobelprize2016 #molecular #motor #nobelprize
#molecularstructure #motormolecules #Feringa
This is an on-site lecture (recorded with Zoom) at the MSc level for chemistry students that are interested in Nanomaterials and Supramolecular Chemistry. Nanotechnology and Photoactive materials.
This lecture introduces molecular machines and their properties are discussed.
Molecular motor molecules that do a translational motion as well as systems that have a rotational operation are discussed.
This lecture starts with rotaxane work performed in Amsterdam (Buma, Brouwer, Woutersen, Leigh).
Than the work of Nobel prize winners Jean-Piere Sauvage, Fraser Stoddart and Ben Feringa is discussed. The rotaxanes of Stoddart are presented, showing the typical structures and properties. Most attention is on double bond isomerization of the light-driven uni-directional rotary molecular motors of Ben Feringa, from Groningen.
Thanks to Prof. Dr. A. M. (Fred) Brouwer for many of the rotaxane slides.
The lecture represents an 'UvA view' of the rotaxane and molecular motors work.
(as evidenced in the thumbnail).
For natural molecular motors see:
ua-cam.com/play/PLjh0slBNmgOl79vncNzwhYI0XkIhLX57U.html
Used in the intro:
Natural motors: translational: kinesine
ua-cam.com/video/y-uuk4Pr2i8/v-deo.html
rotational: ATP-ase:
ua-cam.com/video/b_cp8MsnZFA/v-deo.html
Feringa motors:
simulation:
ua-cam.com/video/I5JgJsjq3Q4/v-deo.html
experiment:
ua-cam.com/video/P-aitePKCkM/v-deo.html
For the recommended talks of the Nobel prize winners, see:
Stoddart:
Very entertaining:
ua-cam.com/video/Pxs6NTCHAdc/v-deo.html
(Fraser is very relaxed!!)
Nobel lecture (8 years later):
ua-cam.com/video/V7DqCz0nQzU/v-deo.html
(Fraser is a bit more nervous….)
Feringa
ua-cam.com/video/4V6Vp2uVQxM/v-deo.html
Rotaxane papers of UvA work:
2001: Photoinduction of Fast, Reversible Translational Motion in a Hydrogen-Bonded Molecular Shuttle
doi.org/10.1126/science.1057886
2010: Operation Mechanism of a Molecular Machine Revealed Using Time-Resolved Vibrational Spectroscopy
doi.org/10.1126/science.1187967
2013: Water lubricates hydrogen-bonded molecular machines
doi.org/10.1038/nchem.1744
Other papers on molecular motors:
pubs.acs.org/toc/chreay/120/1
doi.org/10.1039/C7CS00245A
doi.org/10.1021/cr0300993
Rotaxanes:
doi.org/10.1021/cr5005869
doi.org/10.1039/C8CS00888D
doi.org/10.1002/ejoc.201900081
Feringa motors:
doi.org/10.1039/D1SC04781G
molecular motors 2
Переглядів: 648

Відео

Quantum dots and the "particle in a box" model. Nobel prize of 2023 "in a nutshell". Nano-particles.
Переглядів 414Рік тому
#nanomaterials #education #photochemistry #nobelprize2023 This is a recorded Zoom lecture at the MSc level for chemistry students that are interested in Nanotechnology and Supramolecular Chemistry. Nanotechnology and Photoactive Nanomaterials. This lecture introduces quantum dots, as semi-conductor nanoparticles. Their structure and properties are discussed. Nanoparticle synthesis. This lecture...
Perovskite on Silicon Tandem Solar Cells: 34.6% PCE, Composition, Components, Hole Transporting SAM
Переглядів 2,4 тис.Рік тому
#tandemsolar #perovskite #solar #photovoltaics #nanomaterials #solarcell #education #photochemistry This is an "on site" lecture (recorded with zoom and edited) at the MSc level for chemistry students that are interested in Nanotechnology and Supramolecular Chemistry. Nanotechnology and Photoactive Nanomaterials. READ FOR FREE: rdcu.be/drNEw This lecture introduces the tandem solar cell materia...
Glow Nation Phosphorescence
Переглядів 59Рік тому
This video shows the long lived emission of commercial powders obtained from GlowNation. They work with charge transfer. Slow charge recombination gives the long-lived emission.
Molecular Symphony: asymmetrically substituted perylene bisimides for energy and electron transfer
Переглядів 195Рік тому
This is a "molecular symphony" of asymmetrically substituted perylene bisimides. Adapted from a presentation given on Cyprus in 2009. Publications that feature in this presentation are: A highly soluble asymmetric perylene-bis (dicarboximide)-acceptor system incorporating a methylene bridged methoxybenzene-donor: solvent dependence of charge transfer interactions doi.org/10.3906/kim-0811-33 Tri...
Long-lived Green Photo-luminescence of Heat Treated Human Bones: the Glow of Cremated Remains
Переглядів 350Рік тому
This video shows the emission of human bone fragments, that were heated at 600 degrees Celsius for a short time. Timing is "real live", size is ~half a centimeter, or ~3 centimeter. Recorded with a Nikon camera (D3300), using a UV photo-flash for excitation. This was obtained during the internship of Emma Schut, as part of the Master of Forensic Science program. With a dark adapted human eye, t...
Reactivity of Molecular Oxygen in Ground and Excited State: Why is Singlet Oxygen Super-Reactive?
Переглядів 7 тис.Рік тому
#chemistry #photochemistry #molecular #education #oxygen #anticancer #quantumphysics #quantumtheory #molecularorbitaltheory This is an edited video-lecture for chemists that are interested in molecular oxygen, photochemistry and singlet oxygen. The triplet ground state of molecular oxygen and the excited state, singlet oxygen, are discussed. (A similar lecture has been presented for BSc student...
Metal Coordination Effects on the Photophysics of Dipyrrinato Photosensitizers. Paula C. P. Teeuwen
Переглядів 9352 роки тому
#education #chemistry #photochemistry #anticancer #molecular #inorganicchemistry #organometallics #theory #chargetransfer This is a recorded (edited) zoom lecture by Paula Teeuwen, presenting her Literature Thesis for her Master of Science degree at the University of Amsterdam. It is intended for chemistry students, PhD students and researchers interested in photochemistry, photodynamic therapy...
Shivan Bissesar presenting on Spin Orbit Coupling in Orthogonal Charge Transfer States: UvA 2021
Переглядів 3092 роки тому
This is a recorded (edited) zoom lecture by Shivan Bissesar about his internship at UvA. It is related to the following scientific publication: Spin Orbit Coupling in Orthogonal Charge Transfer States: (TD-)DFT of Pyrene-Dimethylaniline by Shivan Bissesar Davita M. E. van Raamsdonk Dáire J. Gibbons René M. Williams Molecular Photonics Group, van ’t Hoff Institute for Molecular Sciences (HIMS), ...
Perovskites II; Crystals, Orbitals and Trap-states in Perovskites-Structural and Electronic Aspects
Переглядів 3 тис.2 роки тому
#perovskite #solar #photovoltaics #nanomaterials #solarcell #education #photochemistry #orbitals #structure This is a recorded Zoom lecture at the MSc level for chemistry students that are interested in Nanotechnology and Supramolecular Chemistry. Nanotechnology and Nanomaterials. Photoactive Nanomaterials. There are ~15 video's in this course In this second lecture on perovskites structural fa...
Using Computational Chemistry to Describe & Understand the SOCT-ISC mechanism -Davita van Raamsdonk
Переглядів 4142 роки тому
This is a recorded (edited) zoom lecture of Davita van Raamsdonk on her Literature Thesis, on the application of computational chemistry to the SOCT-ISC mechanism. This is part of the MSc program at the University of Amsterdam. Her literature thesis work is incorporated into the following publication: Her work is used in the main text, but especially in the Supplementary Material, where her Lit...
Spin Orbit Coupling in Orthogonal Charge Transfer States: TD-DFT of Pyrene-Dimethylaniline. RMW-UvA
Переглядів 9752 роки тому
#education #photochemistry #orbitals #electrons This is a recorded (edited) zoom lecture related to the following scientific publication: Spin Orbit Coupling in Orthogonal Charge Transfer States: (TD-)DFT of Pyrene-Dimethylaniline by Shivan Bissesar Davita M. E. van Raamsdonk Dáire J. Gibbons René M. Williams Molecular Photonics Group, van ’t Hoff Institute for Molecular Sciences (HIMS), Univer...
"A colourful_ phd" - Instagram report - Dáire J. Gibbons - Porphyrin Research in POLYTHEA
Переглядів 2172 роки тому
This is an edited screen recording of the instagram page of Dáire J. Gibbons. "A Colourful_PhD" is the name of this instagram page. colourful_phd The PhD Thesis of Daire can be found here: hdl.handle.net/11245.1/59fd71af-9b84-4225-9e6d-8cb70f7c1a17 He worked within www.polythea.eu/news-2/ Music: "By the Fireplace", (from UA-cam Editor). Daire 4 Insta Publish 24-01-2022
Black Silicon Solar Cell materials: Genesis, Development and Nano-structure: from Mazur to MACE-RMW
Переглядів 6862 роки тому
This is a recorded hybrid Zoom lecture at the MSc level for chemistry students that are interested in Nanotechnology and Supramolecular Chemistry. Nanotechnology and Nanomaterials. Photoactive Nanomaterials. There are ~15 video's in this course This lecture introduces Black Silicon as solar cell material for photo-detectors, photo-catalysis and anti-bacterial materials. Their structure and meth...
The Photochemistry of Pyrene II - Nature of the Excimer, Orbitals, Vibronic Coupling - Williams, UvA
Переглядів 1,6 тис.2 роки тому
This is a lecture at the MSc level for chemistry students that are interested in molecular photochemistry. From the nature of the excimer to the orbitals and configuration interaction to interaction of electronic transitions and vibrational transitions. Learning objectives: The nature of the excimer is an excitonic interaction with only a slight charge transfer interaction. The exciton is deloc...
Marcus Waves: Marcus theory in 3 dimensions with changing parameters
Переглядів 833 роки тому
Marcus Waves: Marcus theory in 3 dimensions with changing parameters
Marcus Waves: Marcus theory in 3 dimensions
Переглядів 1623 роки тому
Marcus Waves: Marcus theory in 3 dimensions
The Photochemistry of Photodynamic (anti-cancer) Therapy: Singlet Oxygen, Reactive Oxygen Species
Переглядів 8 тис.3 роки тому
The Photochemistry of Photodynamic (anti-cancer) Therapy: Singlet Oxygen, Reactive Oxygen Species
Photoinduced Electron Transfer - The Semi-Classical Marcus-Levich-Jortner Theory. RE-EDIT - RMW, UvA
Переглядів 1,8 тис.3 роки тому
Photoinduced Electron Transfer - The Semi-Classical Marcus-Levich-Jortner Theory. RE-EDIT - RMW, UvA
The Exciplex: Charge Transfer Emission and Absorption of Pyrene and Fullerene aniline complexes
Переглядів 1,9 тис.3 роки тому
The Exciplex: Charge Transfer Emission and Absorption of Pyrene and Fullerene aniline complexes
The Shockley-Queisser Limit: Theoretical limits of solar cells and how to surpass them. RMW-UvA
Переглядів 6 тис.3 роки тому
The Shockley-Queisser Limit: Theoretical limits of solar cells and how to surpass them. RMW-UvA
My lectures in CHINESE! How to translate and change subtitles in YouTube (No Sound, see settings!)
Переглядів 4114 роки тому
My lectures in CHINESE! How to translate and change subtitles in UA-cam (No Sound, see settings!)
Charge Recombination and Intersystem Crossing in PMI-Carbazole Dyads, Davita van Raamsdonk, MSc, UvA
Переглядів 7914 роки тому
Charge Recombination and Intersystem Crossing in PMI-Carbazole Dyads, Davita van Raamsdonk, MSc, UvA
Photoinduced Energy Transfer, Re-Edit, René M. Williams, UvA. Förster and Dexter mechanims. FRET.
Переглядів 2,4 тис.4 роки тому
Photoinduced Energy Transfer, Re-Edit, René M. Williams, UvA. Förster and Dexter mechanims. FRET.
Perovskite Solar Cell Materials: Introduction, Structure, Composition, Doping, Defects -Edit RMW-UvA
Переглядів 41 тис.4 роки тому
Perovskite Solar Cell Materials: Introduction, Structure, Composition, Doping, Defects -Edit RMW-UvA
Making Triplets from Photo-generated Charges, Observations, Mechanisms and Theory, (Edited) RMW, UvA
Переглядів 2 тис.4 роки тому
Making Triplets from Photo-generated Charges, Observations, Mechanisms and Theory, (Edited) RMW, UvA
Organic Solar Cells: Photo-active Nanomaterials - Nanotechnology and Nanomaterials 8, RMW, UvA
Переглядів 5844 роки тому
Organic Solar Cells: Photo-active Nanomaterials - Nanotechnology and Nanomaterials 8, RMW, UvA
Artificial Supramolecular Systems Inspired by Nature - Nanotechnology and Nanomaterials 7, RMW, UvA
Переглядів 5284 роки тому
Artificial Supramolecular Systems Inspired by Nature - Nanotechnology and Nanomaterials 7, RMW, UvA
Gecko's Feet and Stealth Airplane Coating - Nanotechnology and Nanomaterials 6, R. M. Williams, UvA
Переглядів 2834 роки тому
Gecko's Feet and Stealth Airplane Coating - Nanotechnology and Nanomaterials 6, R. M. Williams, UvA
Moore's Law and Transistor Size - Nanotechnology and Nanomaterials 5, René M. Williams, UvA.
Переглядів 3204 роки тому
Moore's Law and Transistor Size - Nanotechnology and Nanomaterials 5, René M. Williams, UvA.

КОМЕНТАРІ

  • @ibrahimmuhammad3445
    @ibrahimmuhammad3445 Місяць тому

    Congratulations for the success recorded

  • @renem.williams9257
    @renem.williams9257 2 місяці тому

    Finally!! It seems my “prayers” have been heard! Recent work (of Gratzel, Sargent and Yuan) shows METHYLAMMONIUM-FREE perovskite materials can give excellent single junction devices with more than 26% PCE: doi.org/10.1038/s41586-024-08103-7 Not formate but acetate is one of the essential additives/components! doi.org/10.3390/molecules29020516 doi.org/10.1007/s43630-023-00500-7 rdcu.be/drNEw

  • @Anna-dw3jo
    @Anna-dw3jo 2 місяці тому

    Congratulations !! Thank you for Your step by step presentation. Thanks to YOU it is possibile to understand the topic.

  • @thayhuongchuyenhoalekhietq6803
    @thayhuongchuyenhoalekhietq6803 2 місяці тому

    Great lecture!

  • @ThreeTwentysix
    @ThreeTwentysix 3 місяці тому

    A very elegant description with Lewis diagrams. Thank you.

  • @arindamnandy6167
    @arindamnandy6167 4 місяці тому

    Thank you sir for your explanation. Can you please share the ppt? Thanks in advance

  • @michaelarulanantham8833
    @michaelarulanantham8833 7 місяців тому

    What would be the Shockley-Queisser limit with monochromatic light and a single junction solar cell tuned to that frequency?

    • @renem.williams9257
      @renem.williams9257 7 місяців тому

      The SQ-limit always refers to a (standard) solar spectrum, not to a single wavelength. But EQE or IQE curves can come close to 100%, or certainly way above 90%. They report the efficiency at every wavelength. see for instance ua-cam.com/video/6gYXdHs5Sfo/v-deo.html at ~ 10:00

    • @michaelarulanantham8833
      @michaelarulanantham8833 7 місяців тому

      @@renem.williams9257 Many thanks for the personal reply and the link.

  • @michaelarulanantham8833
    @michaelarulanantham8833 7 місяців тому

    Great video, will have to watch it a few times

  • @PravdaSeed
    @PravdaSeed 7 місяців тому

    🧞 perovskite 💙🌀🇷🇺🌀💙

  • @saddiqueakbar4774
    @saddiqueakbar4774 8 місяців тому

    Dear Professor I am searching postdoc in solar Cells. Please help me to find a research position. Thank u

  • @XiaoranHu-u9k
    @XiaoranHu-u9k 8 місяців тому

    Thanks from a peer professor! Great video.

  • @hichamcharifi9634
    @hichamcharifi9634 8 місяців тому

    TOP

  • @TrulyNaturalMom
    @TrulyNaturalMom 10 місяців тому

    Thank you for this information of biochemistry’s use of photonic light. I use a device to introduce light & frequency to heal. This is a great explanation- because NO2 is the best way to heal inflammation and pain.

  • @petevenuti7355
    @petevenuti7355 11 місяців тому

    Has FRET ever been experimentally evaluated in a medium with an index of refraction less than one? (FTL phase velocity)

    • @renem.williams9257
      @renem.williams9257 11 місяців тому

      FRET in Metamaterials is rather popular in research: doi.org/10.1038/s42005-023-01347-1 doi.org/10.1021/acsphotonics.8b00484 doi.org/10.1016/j.nanoen.2020.105226 Meta materials can have a negative refractive index.

  • @petevenuti7355
    @petevenuti7355 11 місяців тому

    Not long ago I saw a demonstration of a simple organic solar cell (fruit juice on TiO) , it got me really thinking. I took some chemistry before switching to computer science, so I knew you needed molecules with lots of conjugate bonds, and spectra in the energy level above the band gap of the semiconductor electrode. So I thought, I'll just get some peryline green from the art store, mix it up with some aniline, maybe some anthraquinone then turn it into a conductive polymer and I might have something better. I was thinking like why hasn't anyone else thought if it... That's an example of the Dunning Kruger effect. Classic. The more I looked into how to do such a solar cell, the more I learned, the more I realized I still need to learn. I am so glad to have found your channel! Very helpful, clearly understandable and very educational thank you very much! Is there a specific video of yours that specificly covers the energy transfer directly into redox reactions? Any intermediate level reading recommendations for my self education? Ideally I would like to design a system for an organic flow battery where the electrolyte gets charged directly by light, therefore removing many conversion steps, charge controllers & other ancillary electronics.. hence greater reliability simplicity and lower cost (given chemical stability) Seeing now how much more is known and how much more research has been done then I initially thought, I still have to ask why hasn't this already been done? What problem hasn't been solved yet?

    • @renem.williams9257
      @renem.williams9257 11 місяців тому

      You could read this: dx.doi.org/10.13140/RG.2.2.16547.30244

  • @petevenuti7355
    @petevenuti7355 11 місяців тому

    Regarding solar cells, with solid state electronics I understand the concept of a "band gap", but I believe with organic chemistry is referred to by different terms and measured in different units , something to do with homo and lumo between the excited states in the absorption & emission spectrum overlaps (I've been thinking of covalently coupling chromophores to conductive polymers) So, my question, _What is the equivalent term in biochemistry and what units does it use?_ I only took a year of chemistry before I switched to computer science so take it easy on me please 😉

    • @renem.williams9257
      @renem.williams9257 11 місяців тому

      Marcus theory applies to photosynthesis: ua-cam.com/video/YFzeMMOvhl0/v-deo.html See also text below this video; the Gunner paper is all about this. ua-cam.com/video/GnPIbH6nM9o/v-deo.html

  • @ru1h
    @ru1h Рік тому

    Great video. I'm still quite confused on the significance of the different acceptors that Miller and Closs used. Im I know they becoming more electron withdrawing does that make the transfer go quicker?. It appears that a few parameters are being investigated

    • @renem.williams9257
      @renem.williams9257 Рік тому

      The acceptor strength changed the driving force, transfer goes faster and faster, up to the optimal rate, than it slows down!!! Inverted region.

    • @renem.williams9257
      @renem.williams9257 Рік тому

      A vibration that mediates the transfer is determined, as well as the internal reorganization energy. Together they form the Huang Rhys factor.

    • @renem.williams9257
      @renem.williams9257 Рік тому

      See also my lecture on Classical Marcus theory.

  • @ru1h
    @ru1h Рік тому

    Would it be right to say that the rate constant of dexter's mechanism inversely proportional to the exponent of the distance between the donor and acceptor while for forster's mechanism; the rate constant is inversely proportional to sixth power of the distance

    • @renem.williams9257
      @renem.williams9257 Рік тому

      Regarding the distance dependence of energy transfer: If we plot the natural logarithm of the rate vs distance, we get al linear curve for the Dexter mechanisms. The slope is negative and gives the beta value. doi.org/10.1021/ja990044b The abscissa gives the fastest rate at close contact. Similar observation have been made for photo-induced electron transfer. doi.org/10.1021/ja00245a014 If we do the same for the Forster mechanism, the curve is not straight, but is curved. www.wiley-vch.de/contents/jc_2111/2008/f800156_s.pdf The rate is proportional to 1/R^6 (see also at 27:00) Only changing the distance in molecular systems, keeping all other parameters the same, is often not that easy. SEE ALSO ADDITION IN TEXT BELOW VIDEO. (identical text). I would say that this agrees with your statement!!

  • @indirakafle7134
    @indirakafle7134 Рік тому

    Thank you so much for your explanation!!

  • @oguzcangokce7636
    @oguzcangokce7636 Рік тому

    Thank you for your detailed presentation!!

  • @saidaidsa1891
    @saidaidsa1891 Рік тому

    If tesla panel can generate 350 watt how much perovskites panel can generate per watt ?🤔🤔

    • @renem.williams9257
      @renem.williams9257 Рік тому

      You can not buy perovskite panels yet!! Tesla panels have a PCE of about 22%. Perovskite on silicon can give more than 30% PCE!! (see NREL chart, 33.7% PCE record). Maybe in ten years you can buy those panels. Now just hero cells in research.

  • @neilryan6258
    @neilryan6258 Рік тому

    You explained this concisely and brilliantly, cheers

  • @gustavomoreira4882
    @gustavomoreira4882 Рік тому

    Professor, excellent lecture! Greetings from the University of Minas Gerais in Brazil. I love the UvA, hope to do a PhD there and have the pleasure of seeing you speak in person.

    • @Anna-dw3jo
      @Anna-dw3jo Рік тому

      Indeed the excellent explanation. All your lectures are a special piece of work.

  • @foroozanfaraji594
    @foroozanfaraji594 Рік тому

    It was covering all the subjects around it as well and also incredibly brief and to the point. I'm so greatful

  • @arijeetsarangi2076
    @arijeetsarangi2076 Рік тому

    Hello Sir , nice explanation. I am also working on Perovskites. There are lot of paper who does defect calculation, they are doing chemical potential phase diagram. Can you provide a tutorial for how to plot a phase diagram..

  • @panananananana
    @panananananana Рік тому

    i thought the direct transition from triplet oxygen to singlet oxygen was spin forbidden?

    • @renem.williams9257
      @renem.williams9257 Рік тому

      Yes indeed! The absorptive and emissive transitions of molecular oxygen are spin-forbidden!! Forbidden transitions still occur! But with a low probability. This implies that the molar absorption coefficient is very low (for the absorption) and the emission is very long lived. The latter is especially influenced by vibronic coupling to the solvent. See: ua-cam.com/video/gbSQkrs49ss/v-deo.html at ~44 to 46 minutes. The absorptive transitions of pyrene to S1 are also forbidden: ua-cam.com/video/OPRLcTzjc_8/v-deo.html

  • @eisvogel.1481
    @eisvogel.1481 Рік тому

    Thank you very much for your explanations!😍

  • @fmoney
    @fmoney Рік тому

    Very Interesting How can we create that photovoltaic or photodetector device that Aalto University researchers made? 132% efficiency?

    • @renem.williams9257
      @renem.williams9257 Рік тому

      Thanks. 132% Power Conversion Efficiency for solar is impossible, according to the Laws of thermodynamics, and the Shockley Queisser limit. ua-cam.com/video/KsP90hT41t4/v-deo.html www.nrel.gov/pv/cell-efficiency.html

  • @jhansidumala
    @jhansidumala Рік тому

    what was the software that was used to determine those parameters

    • @renem.williams9257
      @renem.williams9257 Рік тому

      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.

  • @Muzeemkhankamaal
    @Muzeemkhankamaal 2 роки тому

    Amazing

  • @DocLow
    @DocLow 2 роки тому

    Great presentation! Thank you for sharing. I had read about Fluorine additive helping improve perovskite stability but I had not heard about the theory of strain relaxation to explain it. Its good to know Zinc and Calcium and other elements could be used too. Vert interesting.

  • @1nammashale
    @1nammashale 2 роки тому

    Excellent presentation. Thank you. I have a question, in PDT why do you want to enhance the generation of triplet state with less QY. I mean what is the purpose? I am curious.

    • @renem.williams9257
      @renem.williams9257 2 роки тому

      The excited triplet state can interact with ground state molecular oxygen (a triplet) and form the very reactive excited state of oxygen (called singlet oxygen). Singlet oxygen can destroy tumor cells. See ua-cam.com/video/gbSQkrs49ss/v-deo.html

    • @1nammashale
      @1nammashale 2 роки тому

      Thank you ❤️

  • @renem.williams9257
    @renem.williams9257 2 роки тому

    It has been a great pleasure to help such a brilliant student to share her talent with the whole world! Flabbergasted by such splendour...

  • @srestsomay3533
    @srestsomay3533 2 роки тому

    Hi Professor. Always a pleasure to see you explaining the complex perovskite chemistry in a simplified way. Thanks for the lecture. I hope you are doing well.

  • @mahsashksh1884
    @mahsashksh1884 2 роки тому

    Thank you so much for your nice lecture. I have a question, how we can consider the molecular orbitals of the octahedral part of perovskites? for instance, [PbBr6]-4, the 5d is completely full, so, we need to consider 6d for interaction? if yes, what its molecular orbital will look like? Thank you, professor.

    • @renem.williams9257
      @renem.williams9257 2 роки тому

      In the second perovskite lecture you can see the orbitals!!

  • @peter.a.tanner
    @peter.a.tanner 2 роки тому

    I listened until 2:18 and it was enough. 1. An excited state is not an exciton (as written later accidents); 2. Dexter (not Dextrer) transfer is not double electron exchange. The orbitals are overlapping before the incident photon comes. 3. There are more than 2 theoretical frameworks for nonradiative energy transfer. 4. Forster and Dexter are not singlet and triplet energy transfer..

    • @peter.a.tanner
      @peter.a.tanner 2 роки тому

      Unfortunately, this type of thinking pervades the chemical literature

    • @renem.williams9257
      @renem.williams9257 2 роки тому

      1: wikipedia: “When a molecule absorbs a quantum of energy that corresponds to a transition from one molecular orbital to another molecular orbital, the resulting electronic excited state is also properly described as an exciton.” OK, excitons are mainly used in solid state physics, but sometime we want to talk to them. There are many types of excitons. I prefer using the words “excited states”. There are also many types of excited states!! 2: Thanks for helping to improve the captioning provided by Google/UA-cam. I now corrected these mistakes. Dexter is often described as double electron transfer. It is also called the exchange mechanism, electron exchange. Yes, orbital overlap plays an important role here. The orbitals mediate the interaction. The transfer is triggered by the photon, the interaction is already there. 3: As written below the video; “There are two important theoretical frameworks that can be used for energy transfer: the Coulomb based Förster Resonance Energy Transfer (FRET) and the Exchange based Dexter mechanism.” There are indeed more mechanism. Even TODAY MSc students presented about energy transfer between graphene and molecules that did not follow Förster. 4: Förster is often used for singlet-singlet energy transfer. Dexter for triplets. But there are examples where both play a role at the same time, competing with each other, as I tell later-on in the video.

    • @peter.a.tanner
      @peter.a.tanner 2 роки тому

      @@renem.williams9257 Thanks for quoting Wikipedia to me. That is about it.

    • @peter.a.tanner
      @peter.a.tanner 2 роки тому

      @@renem.williams9257 Anyway, it's good to put science on UA-cam. Keep it up

    • @lineakristensen1821
      @lineakristensen1821 2 роки тому

      @@peter.a.tanner you ok mate?!

  • @InquilineKea
    @InquilineKea 2 роки тому

    omg so relevant for clarice quantum biology

    • @renem.williams9257
      @renem.williams9257 10 місяців тому

      Than this might interest you too: doi.org/10.34133/icomputing.0072

  • @dmajumdar2059
    @dmajumdar2059 2 роки тому

    i have been looking for a detailed video on FRET for a very long time! Great to finally have one!!

  • @mohsentamtaji9130
    @mohsentamtaji9130 2 роки тому

    Great talk

  • @loveall2941
    @loveall2941 2 роки тому

    What is the possible commercial values of doping concentration in methyl ammonium tin triiodide perovskite solar cells?

    • @renem.williams9257
      @renem.williams9257 2 роки тому

      The optimal doping percentages depend on the materials. Below 3 mol% relative to Sn (or Pb) is often optimal. Reports between 0.15% and 2.5% can be found, for Pb materials.

    • @loveall2941
      @loveall2941 2 роки тому

      @@renem.williams9257 can you answer like what is the upper limit of experimentally achievable doping concentration of methyl ammonium tin triiodide as an absorber layer? Is it 3.5 x 10*18 or more?

    • @renem.williams9257
      @renem.williams9257 2 роки тому

      @@loveall2941 It is not p-doping and n-doping like with silicon, it is compositional engineering. Perhaps similar to alloying of steel with carbon. You can choose the amount of dopant / alloy composition during the fabrication. More than 5% often results in segregation.

  • @yinonderee3666
    @yinonderee3666 2 роки тому

    Dear Rene', if I may i have further questions. 1) in this video you focus on that orthogonality is critical for ISC but we need to satisfied another criterion that is the proximity of the energy of the T1 and the C.T orthogonal state, is that right? 2) can in that case of C.T state and T1 state be in equilibrium? or maby C.T state that is singlet and C.T that is triplet? best regards, Yinon.

    • @renem.williams9257
      @renem.williams9257 2 роки тому

      The energy difference plays a role. It is basically Marcus theory, so Delta G and lamdba are important. If T1, singlet CT and triplet CT are close, equilibrium can play a role. See also video of Peter Hore on magneto reception in avian navigation. in Playlist. ua-cam.com/video/FytxLiHlah4/v-deo.html

  • @mhd112211
    @mhd112211 2 роки тому

    Cheers!

  • @yinonderee3666
    @yinonderee3666 2 роки тому

    The requirement for the orthogonality of the D-A groups does not exist in the exited state?(the process is fro LE(1) to CT(1) ) so why focus on the angles in the ground state? best regards, Yinon.

    • @renem.williams9257
      @renem.williams9257 2 роки тому

      Dear Yinon, it is indeed even better to look at the conformations in the excited states! Especially if we go from CT(1) to LE(3) (local triplet excited state, also called T1). In fact we have recently reported on such excited state geometries: ua-cam.com/video/x-nfr7pFmcc/v-deo.html ua-cam.com/video/FlbV6tRUlYc/v-deo.html doi.org/10.3390/molecules27030891

    • @ינוןדרעי-ל7ת
      @ינוןדרעי-ל7ת 2 роки тому

      Thank you!

  • @harshaagrawal2473
    @harshaagrawal2473 2 роки тому

    How to understand in ur absorption spectra charge transfer band is there?

    • @renem.williams9257
      @renem.williams9257 2 роки тому

      For a good electron donor acceptor pair it is a new absorption band, red-shifted relative to the separate components. For instance: tetracyanoethylene (TCNE) in toluene, anisole and veratrole solvent (solvent is donor here).

  • @mohammadrahil9678
    @mohammadrahil9678 2 роки тому

    Thank You Sir, for sharing such a valuable information video.

  • @alexandreteodoro6570
    @alexandreteodoro6570 2 роки тому

    I was studying this topic by myself and just found this video. Thank you very much professor, it was very helpfull.

  • @mattkunq
    @mattkunq 3 роки тому

    Thumbnail at 54:00

  • @MohammedIslamElshiekhElsmani
    @MohammedIslamElshiekhElsmani 3 роки тому

    Interesting!!

  • @amit9837
    @amit9837 3 роки тому

    Prof René M. Williams your talks are so amazing! thank you!!

  • @DanielAlejandroHeredia
    @DanielAlejandroHeredia 3 роки тому

    Great lecture!!!