Capability for Science of the Future: Ultrafast Spectroscopy Laser Centre at Sheffield, USLS

我们建议建立一个超快激光光谱系统，通过利用现代技术进步，使我们能够以许多不同的方式研究分子和材料吸收光后立即发生的事情，然后是长期的结果。光与物质的相互作用是现代科学中最重要的领域之一。它支撑了基于光子学的新材料的新兴技术，这些材料可用于未来的通信、计算、显示器和照明设备；预计这一技术部门在中短期内的经济影响将非常大。光与物质的相互作用也是通过光合作用将阳光转化为能量的基础，而光合作用是地球上生命的基础。人们对自然光合作用非常了解，而且非常有效：现在的目标是建立模仿自然光合作用系统关键特性的人工系统，以便我们最终能够收获阳光作为能源，并为人类长期、可持续的、不依赖化石燃料、不会造成污染的能源生产做出重大贡献。人工光合作用的任务是广泛的：我们不仅需要构建能够有效地捕捉光的分子系统或材料，而且它们还需要能够使用它来直接产生能量(例如，作为光伏电池中的电能)，或者能够驱动化学反应，作为太阳能燃料(例如，通过提供能量将废物二氧化碳转化为燃料甲醇)。所有对光/物质相互作用的研究--无论是针对理解自然、利用能量、或构建新的光通信设备-需要能够测量分子和材料在光被吸收后立即发生的极快变化。最初的变化发生在飞秒的时间尺度上，可能涉及电子密度的移动或键振动的变化，这是可以检测到的。在此之后，捕获的能量通过分子组装或材料流动，这种电荷或能量从一个地方到另一个地方的移动--可以发生在从皮秒到微秒的时间尺度--再次可以被详细地可视化。最后，任何后续的化学变化可能发生在慢至毫秒的时间尺度上都将被可视化。其结果将是，当光子被吸收后，能够准确监测材料和分子组件中发生的事情；当能量或电子随后通过材料和/或导致结构变化；以及随着能量最终以各种方式使用，从发光到触发化学反应。我们将建造的设施在英国大学系统中将是独一无二的，因为它将在一个单一、集成的设施中结合超快光谱的不同方面，这将使单一地点和单一样本能够进行最全面的一系列测量。该设施将结合各种可测量的时间尺度(从飞秒到毫秒的所有事件，跨越11个数量级)；从低能振动到高能电子跃迁的连续能量谱；以及能够实时探测结构和电子性质变化的各种讯问技术。这将为谢菲尔德和更广泛的英国社区的研究人员提供研究光与物质相互作用的最先进工具。通过创建一个“超快枢纽”，将与他们共享该设施。这将促进国家重要领域的广泛科学，并可能使社会受益于技术发展(如新的基于光子学的材料和设备)以及利用阳光进行更清洁、更廉价的能源生产。

We propose to build an ultrafast laser spectroscopy system which, by exploiting modern technological advances, will allow us to examine in many different ways what happens to molecules and materials after they absorb light, both immediately after absorption and then the longer-term consequences.The interaction of light with matter is one of the most important areas in modern science. It underpins the emerging technology of new photonics-based 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 - which is fundamental to life on earth. Natural photosynthesis is quite well understood and is sufficiently effective for Nature's needs: the goal now is to 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 photosynthesis 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 the fuel methanol).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 once 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 facility that we will build will be unique in the UK university system as it will combine diverse aspects of ultrafast spectroscopy in a single, integrated facility which will enable the most comprehensive set of measurements possible at a single site with a single sample. The facility will combine a wide range of timescales that can be measured (all events 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 interrogation techniques that allow changes in structure and electronic properties to be probed in real time. This will provide researchers both in Sheffield and the wider UK community - with whom the facility will be shared, by creating an "ultrafast hub" - access to a state-of-the-art tools for studying light-matter interactions. This will facilitate a wide range of science in areas of national importance and potentially benefit society from technological developments (such as new photonics-based materials and devices) and from cleaner and cheaper energy generation using sunlight.