Maximising Shared Capability of the Ultrafast Spectroscopy Laser Laboratory at Sheffield

Lead Research Organisation: University of Sheffield
Department Name: Chemistry

Abstract

The interaction of light with matter is one of the most important areas in modern science. It underpins the emerging technologies of photonics materials that can be used in the communications, computing, displays and lighting devices of the future; the economic impact of this technology sector in the short-to-medium term is predicted to be very large. Interaction of light with matter is also the basis of the conversion of sunlight into energy by photosynthesis and is fundamental to life on earth. Natural photosynthesis is remarkably effective: the goal now is build artificial systems that mimic the key properties of natural photosynthetic systems so that we can, finally, harvest sunlight as an energy source and make a major contribution to mankind's long-term sustainable energy generation that is not fossil-fuel dependent and is not polluting. The tasks of artificial light-harvesting are extensive: not only do we need to construct molecular systems or materials that can capture light effectively, but they need to be able to use it to either generate energy directly (e.g. as electricity in photovoltaic cells), or to drive chemical reactions that provide 'stored energy' as a solar fuel (e.g. by providing energy for conversion of the waste-product CO2 to liquid fuels).

Ultrafast laser spectroscopy allows one to examine in many different ways what happens to molecules and materials after they absorb light, both immediately after absorption and on a timescale of years.

All research in light/matter interactions - whether it is directed at understanding nature, harnessing energy, or constructing new optical communications devices - requires the ability to measure the extremely fast changes that occur in molecules and materials immediately after light is absorbed. The initial changes take place on a timescale of femtoseconds and may involve movement of electron density, or changes in bond vibrations, which can be detected. Subsequent to this the captured energy 'flows' through the molecular assembly or material, and this movement of charge or energy from place to place - which can occur on timescales from picoseconds to microseconds - can again be visualized in detail. Finally any subsequent chemical changes that may occur on timescales as slow as milliseconds will be visualized. The result will be the ability to monitor exactly what happens in materials and molecular assemblies when the photon of light is absorbed; as the energy or an electron subsequently moves through the material and/or results in structural changes; and as the energy is finally used in various ways from luminescence to triggering chemical reactions.

The laboratory that we build is unique in the UK university system as it combines diverse aspects of ultrafast spectroscopy in a single, integrated facility which will enable the comprehensive set of measurements at a single site with a single sample. It will cover a wide range of timescales - from femtoseconds to milliseconds, which spans 11 orders of magnitude; a continuous spectrum of energies from low-energy vibrations to high-energy electronic transitions; and a wide range of detection methods that allow changes in structure and electronic properties to be probed. This will provide researchers both in Sheffield and the wider UK scientific community - with whom the facility is shared - access to state-of-the-art methods to studying light-matter interactions. This unique facility enables a wide range of science projects in areas of national importance and potentially benefit society from technological developments (such as more efficient lighting) and from cleaner, cheaper energy generation using sunlight.

Since all our methods are based on cutting-edge technology, they require highly professional scientists to ensure that the equipment works to its full potential, to help diverse groups of scientists to use it to reach out to the very edge of technology and knowledge.

Planned Impact

The impact of the extremely broad range of scientific endeavours in light-matter interactions which has been enabled already by the operation of the USLS along with the new directions which have been inspired by its existence, and have emerged since the capital equipment award, may be just as extensive and far-reaching, with the potential to improve diverse aspects of our lives.
Economic. Economic impact will occur in both the medium and long terms. Medium-term benefits will be mostly from the more applied research projects, that are linked to spin-out companies or industrial sponsors. A key example is photonics technologies which currently underpin > 10% of the EU economy with a projected global market of Eur 600 Bn by 2020.

These traditionally include all-optical communications, quantum computing and laser technology, energy efficient lighting, photonic diagnostics for healthcare, safety and security - embrace new developments, such as perovskite solar cells, thin-film optoelectronics, new directions in artificial photosynthesis based on recent discoveries. Likewise, organic optoelectronics are predicted to be a disruptive technology enabling market growth impossible with existing technology - the past few years have seen emergence of new directions with potential to deliver step-change in technology for sensors, organic solar cells, and a new era in computing - excitonic optical computing.

Improvements in energy generation - arising from a range of research spanning chemistry, physics, engineering and synthetic biology - will have long term economic benefits for everyone. Although many of these projects are focussed on the blue-skies research, they have potentially huge benefits. Key beneficiaries: energy sector in the medium term, society as a whole in the long term due to lower energy costs and greater sustainability.

Synthetic transport fuels will be in demand as fossil-based fuels are phased out. Approaches to CO2 reduction into fuels are now exploring making dimethylether (DME) as a low-particulate emission liquid fuel, a diesel replacment. Volvo and Ford trucks in North America have developed DME fleets.
Key beneficiaries: energy sector in the medium term, society as a whole in the long term.

Societal benefit follows economic benefit. In the long term society as a whole will have higher quality of life from the reduced costs and cleaner environment associated with improved renewable energy generation, as well as access to improved photonics technologies for day-to-day issues from communications to healthcare.
In the energy field in particular, economic benefits for a few translate into global societal benefits for all.

Knowledge. The new knowledge arising will initially benefit academia, but as impacts and exploitations emerge this knowledge will become integrated into the areas of commerce, education and indeed everyday life. We will ensure maximum benefit from the new knowledge via engagement with schools outreach and public understanding events. It is important to raise awareness of the sustainable alternatives to conventional energy sources: our programme of public lectures, school events, and Science week events will emphasise this. Key beneficiaries: the public, from improved understanding of issues surrounding applications of light-based technologies and energy in general.

People. A major long-term impact will arise from training and development of early-career researchers. Given the importance of light-based methods in the research that underpins fields from photosynthesis to spintronics, a trained pool of young scientists is key to maintain the UK's competitive position in these fields, ensure the sustainability of our science and industry base on a 10-50 y timescale. Key beneficiaries: the researchers, UK industry (med. term), and society as a whole. The unique training will enhance the carrier prospects of talented young researchers to the benefit to them and the society.

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