Electron Paramagnetic Resonance (EPR) spectroscopy—a technique that probes materials with unpaired electrons—is getting a major upgrade at the UK’s National Research Facility in Manchester. Unpaired electrons control the magnetic and electronic behaviour of materials, from biological molecules to advanced magnets. But studying them is often slow or impossible when samples are tiny, dilute, or watery. The current benchtop EPR system is already running at full capacity, creating a bottleneck for UK researchers. This grant funds two new capabilities. A multi-harmonic detection system will boost sensitivity across five microwave frequencies, cutting measurement times for normal samples and making it possible to study difficult ones—like biological tissues with high water content. A portable benchtop spectrometer will add extra capacity for the most common screening frequency, X-band, and can be taken off-site to hospitals or user labs. This allows researchers to measure sensitive samples under controlled conditions before bringing them to the facility for deeper analysis. If successful, the upgrade will widen access for early-career researchers and doctoral students, and open EPR to new fields—particularly medical diagnostics, where paramagnetic species in tissue samples can now be studied more reliably.
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Electron Paramagnetic Resonance (EPR) spectroscopy, also known as Electron Spin Resonance (ESR), is possibly the most powerful technique for characterisation of paramagnetic materials, i.e. that contain unpaired electrons. Unpaired electrons give rise to the magnetic and electronic properties of materials and often govern reactivity when present, hence understanding their environment and behaviour is important. Paramagnets are ubiquitous from biological processes to magnetic materials; hence EPR is an essential tool in physics, chemistry, materials and biological sciences. The EPSRC funds a National Research Facility (NRF) for EPR, located in the Photon Science Institute (PSI) at The University of Manchester (UoM), providing access to state-of-the art experimental techniques and expertise for the UK academic community. Crudely, there are two ways to do EPR spectroscopy: continuous wave (cw) EPR and pulsed EPR, which give complementary information. Our two previous successful core equipment grants have been used to enhance the capabilities of pulsed EPR in the NRF. This proposal is designed to markedly enhance continuous wave capabilities and capacity, through two related strands: (i) The newly commercialised multi-harmonic detection system will provide enhanced sensitivity, and its modular nature will allow it to be used across all five microwave frequencies that we currently operate: L-, S-, X-, K- and Q-bands (spanning 1-34 GHz). This will enable more ready study of samples with low spin concentrations or that are sample-limited, and it will shorten acquisition times for “normal” samples. It will also make study of lossy dielectric samples (e.g. higher water content) more straightforward. (ii) A self-contained benchtop spectrometer system will significantly enhance capacity for cw X-band measurements. X-band is the most common screening frequency, and it is the frequency most commonly used in research applications. In addition, the kit will have new benchtop capabilities for sample cooling between 300 and 5 K (using an existing closed-system cryostat), transient signal detection, and multi-harmonic detection [item (i)]. Our current benchtop system is operating to capacity. Moreover, because the benchtop system is portable it will also enable us to take high-end research capability in cw EPR ‘on the road’, including for outreach and training events, and also to measure ‘difficult’ samples in the users’ own laboratory, where those samples are under greater control than if they were brought off site to the EPR NRF. Benchmarking in this way will then allow much greater confidence in results when those samples are subject to more detailed measurements at the NRF. A particular example of off-site use is for medical samples in a hospital, which is currently being negotiated with a user of the NRF. These extensions to multi-harmonic detection and expansion of state-of-the-art benchtop EPR capabilities will increase the capacity for EPR for all users of the NRF across the UK, including ECRs and doctoral students, and the new capabilities will widen the user base. To contact the National EPR Facility and Service, please email: epr@manchester.ac.uk and web-site: https://www.chemistry.manchester.ac.uk/epr/ EPR Team: David Collison (DC); Eric McInnes (EJLM); Alice Bowen (AMB); Floriana Tuna (FT); Muralidharan Shanmugam (MS); Adam Brookfield (AdB)
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