A new laser-based instrument will track molecules in the first quadrillionth of a second after they absorb light, capturing the fleeting atomic movements that determine a material’s properties. Current spectroscopic tools struggle to follow these ultrafast dynamics in materials that are opaque or weakly emissive—such as a photocatalyst mounted on a solid surface. The FASTCHEM facility overcomes this by combining femtosecond transient absorption, reflection, and fluorescence up-conversion in a single setup, covering times from femtoseconds to milliseconds across ultraviolet to near-infrared wavelengths. A custom horizontal sample mount also lets researchers study thin films without gravity-induced distortions that plague vertical setups. If successful, FASTCHEM will allow scientists to design photoresponsive materials based on how their structure changes over time, not just static snapshots. This could lead to better sunscreen filters that block harmful UV radiation while being less toxic to marine life, more efficient photocatalysts for producing clean fuels, and improved materials for medical imaging and light-based therapies. The facility is designed as a multi-user resource, prioritising access for early-career researchers and contributing to UK challenges in clean growth, future mobility, and healthy ageing.
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Transient absorption spectroscopy (TAS) is a widely used spectroscopic technique based on detecting photoinduced absorption changes in a sample. If the excitation and detection light sources used in TAS have femtosecond (i.e. one millionth of one billionth of a second) time resolution, then we have a viewing glass into the fundamental processes in operation immediately after the molecule, or material, absorbs light. This is incredibly powerful as molecular transformations triggered by absorption of light occur on the timescale of molecular vibrations which typically happen on tens to hundreds of femtosecond (fs) timescales. The ability to observe these ‘ultrafast’ dynamics and assess how they are influenced by structural changes is formidable as the extra dimension of dynamics, allows us to transform the structure-function approach to molecule and material design to a more complete structure-dynamics-function approach, allowing us to enhance the performance of materials in photomedicine, photostability, photocatalysis, and photonics. At the heart of the UltraFAST PhotoCHEMistry Induced by Light – ‘FASTCHEM’ – facility is a bespoke fs-TAS instrument that, in addition to having fs-TAS capabilities, has transient reflection and fluorescence up-conversion capabilities meaning we can investigate materials that are also poorly transmissive – TAS requires light to transmit through sample – and weakly light emissive (e.g., photocatalyst mounted on a non-transparent medium). Combined, these capabilities span the time-window of femtoseconds to milliseconds, with spectral coverage from ultraviolet to near-infrared. The result is an instrument that tracks photoinduced dynamics in exceptional detail; the kind of detail that is essential if one is seeking to fine tune the performance of photoresponsive materials. There is also a custom-built variable sample mounting arrangement, enabling both the more traditional vertical setup and new horizontal setup. This enables potential users to study thin films using the horizontal option, without concerns about gravitational effects causing sample inhomogeneities that can compromise many experiments which employ vertically mounted thin films. The combination of these capabilities within a single laboratory renders FASTCHEM globally unique. FASTCHEM will be multi-user in nature, its principal aim to enable discovery-led research achieved through a facility structure and an ecosystem of researchers with a range of expertise, in particular early career researchers. FASTCHEM’s objectives will be to contribute towards addressing complementary institutional, UKRI and industrial research challenges around Clean Growth (through materials for alternative fuels), Future Mobility (through materials for storage), Aging Society (through materials for healthcare), and, indirectly, Artificial Intelligence and Data Economy (through material theory/computation). Through its unique combination of capabilities, FASTCHEM will enable transformative science benefitting society. For example, such structure-dynamics-function approaches will lead to next generation sunscreen filters that protect humans from the deleterious effects of ultraviolet radiation exposure, and are less toxic to the environment. To deliver our aim of enabling discovery-led research and achieve our objectives contributing towards the vital research challenges listed supra, we will: (1) develop a fully functioning FASTCHEM facility; (2) implement experimental methods to deliver our four Primary Scientific Challenges (PSC) which are new molecules and materials for photomedicine, photostability, photocatalysis and photonics; (3) utilise a transparent and fair access management model; (4) deliver a user support and training programme with our project partner Ultrafast Systems; (5) provide a supportive career and professional development program for our experimental officer; and (6) establish a roadmap towards expanding the user base and training the next generation of scientists.
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