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'.

Publications

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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 31/03/2021 Luke Smith