Modelling ultrafast molecular photo switches
Lead Research Organisation:
University of Leeds
Department Name: Sch of Chemistry
Abstract
Molecular switches form the basis of human vision. The retinal molecule in the rhodopsin complex absorbs visible light which leads to photo isomerisation. From experiments with ultrafast laser pulses, this process is known to be extremely fast, with photoproduct formation within 200 fs (1 fs is ten to the power minus 15 seconds). A combination of laser experiments and theory are used to study how the motion of the atoms in the retinal molecules happen after absorbing light. Retinal is an example of an ultrafast photo switch that operates in a highly complex environment.
With the recent development of X-ray free electron lasers, new experiments on the motion of molecules after absorbing light become possible, which will lead to a more detailed understanding of such photo switches.
The goal of this project is to develop theoretical treatments of photo switches in a complex environment, where interactions with the solvent or the molecules surrounding the photo switch lead to strong damping. The objective is to create such a theory, and then apply it to molecular photo switches to produce simulation results that can be compared with experiment. The essential ingredient of the model is strong damping in combination with quantum mechanics. Quantum effects are important because of the nature of the light excitation. The complex environment of the photo switch molecule leads to damping of its motion, and also to effects such as decoherence.
The basic understanding and modelling tools that will result from this project will be needed to interpret and complement experimental studies on photo switches. They can be used to design such molecules for applications. These could be used in future fast electronics, or in molecular machines. This research project fits well in the EPSRC research area 'Computational and theoretical chemistry'.
With the recent development of X-ray free electron lasers, new experiments on the motion of molecules after absorbing light become possible, which will lead to a more detailed understanding of such photo switches.
The goal of this project is to develop theoretical treatments of photo switches in a complex environment, where interactions with the solvent or the molecules surrounding the photo switch lead to strong damping. The objective is to create such a theory, and then apply it to molecular photo switches to produce simulation results that can be compared with experiment. The essential ingredient of the model is strong damping in combination with quantum mechanics. Quantum effects are important because of the nature of the light excitation. The complex environment of the photo switch molecule leads to damping of its motion, and also to effects such as decoherence.
The basic understanding and modelling tools that will result from this project will be needed to interpret and complement experimental studies on photo switches. They can be used to design such molecules for applications. These could be used in future fast electronics, or in molecular machines. This research project fits well in the EPSRC research area 'Computational and theoretical chemistry'.
Organisations
Publications
Smith LD
(2019)
Quantum dissipative systems beyond the standard harmonic model: Features of linear absorption and dynamics.
in The Journal of chemical physics
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509681/1 | 01/10/2016 | 30/09/2021 | |||
| 1939680 | Studentship | EP/N509681/1 | 01/10/2017 | 30/09/2021 | Luke Smith |
| Description | The award abstract presents the goal of this ongoing project as the development of theoretical treatments of photo switches in a complex environment. Already, significant progress has been made towards meeting this objective. Open quantum system theory has been utilised, specifically the stochastic Schrodinger equation, to model the damping effects of the environment on the quantum motion of a photo switch. This has been implemented in simulations that study models relevant to photo switch systems, such as the stiff-stilbene photo switch which has a proposed use as a molecular motor. These simulations gave results on the motion of such a photo switch and features that could be observed in linear absorption spectra, which can be produced experimentally by using ultrafast laser pulses. The full details have been published in the the Journal of Chemical Physics which I have linked to this award in the publications section. |
| Exploitation Route | I am already in the process of conducting follow up research on a more realistic treatment of the stiff-stilbene photo switch, which includes some of the molecular motions that are important to understanding the complexity of the experimentally produced absorption spectra. In addition to this, important temperature effects of the environment will be incorporated in an extension of the method using the recently developed "Hierarchy of Pure States (HOPS)" approach. These temperature effects are likely to be of importance in understanding the role of the environment on the motion of a photo switch. The results of simulations produced using this extended, and more accurate method could then be used to interpret the experimental results of stiff-stilbene featured in recent literature. Consequently, this should increase understanding and uncover design principles important for future applications. I aim to conduct a future study considering the application of this method to more complex photo switch systems such as the retinal photo switch. The result of such a study could benefit the development of photo switches designed to restore visual function to blind retina. Furthermore, it may increase understanding in the importance of quantum mechanics in biological systems. |
| Sectors | Electronics,Pharmaceuticals and Medical Biotechnology |