Capital Award for Core Equipment 2022/23, National Research Facility for Electron Paramagnetic Resonance Spectroscopy
Lead Research Organisation:
University of Manchester
Department Name: Chemistry
Abstract
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. Pulsed EPR is a much higher resolution technique (allowing measurement of much weaker interactions involving the unpaired electron) and also gives access to time-resolved information. However, such experiments can require access to very low temperatures (<10 K) otherwise signal response may be non-existent or data collection very slow, requiring long data collection to get acceptable signal-to-noise (e.g. due to low paramagnet concentration). It is common for an experiment on a single sample to last a week of continuous measurement. As a consequence, the three pulsed EPR spectrometers that the EPR NRF currently runs are by far and away the most oversubscribed pieces of instrumentation. Two of those spectrometers have cooling systems that give base temperature of ca. 2 K and can be remotely monitored and controlled, but the third only reaches 10 K and requires manual control. Allied to a forthcoming upgrade, all pulsed EPR frequencies will have the same sample temperature control, thereby maximising flexibility and throughput across four frequency bands (two per spectrometer platform): X-/Q-, Q-/S- and X-/L-bands, noting that Q- and X-band are most requested frequencies by the user community.
There has been a large increase in the interest in and use of optically excited samples monitored by EPR spectroscopy, which are primarily serviced by either pulsed or transient EPR methods. Like many pulsed experiments, data collection can be slow, and the inclusion of pulsed light excitation into the microwave (and sometimes radiofrequency) pulse sequences lengthens measurement time further. Installing a fast, high power, tunable laser will increase capacity and efficiency of these optical experiments. In conjunction with our slower, lower power tunable laser, the EPR spectrometers will be able to deliver 'two colour' experiments, for which there is also growing interest.
The extension to cooling and optical excitation capability will increase the capacity for pulsed 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/
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. Pulsed EPR is a much higher resolution technique (allowing measurement of much weaker interactions involving the unpaired electron) and also gives access to time-resolved information. However, such experiments can require access to very low temperatures (<10 K) otherwise signal response may be non-existent or data collection very slow, requiring long data collection to get acceptable signal-to-noise (e.g. due to low paramagnet concentration). It is common for an experiment on a single sample to last a week of continuous measurement. As a consequence, the three pulsed EPR spectrometers that the EPR NRF currently runs are by far and away the most oversubscribed pieces of instrumentation. Two of those spectrometers have cooling systems that give base temperature of ca. 2 K and can be remotely monitored and controlled, but the third only reaches 10 K and requires manual control. Allied to a forthcoming upgrade, all pulsed EPR frequencies will have the same sample temperature control, thereby maximising flexibility and throughput across four frequency bands (two per spectrometer platform): X-/Q-, Q-/S- and X-/L-bands, noting that Q- and X-band are most requested frequencies by the user community.
There has been a large increase in the interest in and use of optically excited samples monitored by EPR spectroscopy, which are primarily serviced by either pulsed or transient EPR methods. Like many pulsed experiments, data collection can be slow, and the inclusion of pulsed light excitation into the microwave (and sometimes radiofrequency) pulse sequences lengthens measurement time further. Installing a fast, high power, tunable laser will increase capacity and efficiency of these optical experiments. In conjunction with our slower, lower power tunable laser, the EPR spectrometers will be able to deliver 'two colour' experiments, for which there is also growing interest.
The extension to cooling and optical excitation capability will increase the capacity for pulsed 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/
