Capital Award for Core Equipment 2022/23, National Research Facility for Electron Paramagnetic Resonance Spectroscopy

电子顺磁共振(EPR)谱，也被称为电子自旋共振(ESR)，可能是表征顺磁材料(即含有未配对电子的材料)的最强大的技术。未成对的电子引起材料的磁性和电子性质，并经常控制存在时的反应性，因此了解它们的环境和行为是重要的。从生物过程到磁性材料，顺磁体无处不在，因此EPR是物理、化学、材料和生物科学中必不可少的工具。EPSRC资助了EPR的国家研究设施(NRF)，该设施位于曼彻斯特大学(UOM)的光子科学研究所(PSI)，为英国学术界提供获得最先进的实验技术和专业知识的途径。粗略地说，EPR谱有两种方法：连续波(CW)EPR和脉冲EPR，它们提供了互补的信息。脉冲EPR是一种分辨率高得多的技术(允许测量涉及未配对电子的弱得多的相互作用)，还提供了访问时间分辨信息的途径。然而，这样的实验可能需要进入非常低的温度(&lt；10K)，否则信号响应可能不存在或数据收集非常慢，需要长时间的数据收集才能获得可接受的信噪比(例如，由于顺磁浓度低)。对单个样本的实验持续一周的连续测量是很常见的。因此，EPR NRF目前运行的三台脉冲EPR光谱仪无疑是超额认购最多的仪器。其中两台光谱仪有冷却系统，基本温度约为2K，可以远程监测和控制，但第三台只能达到10K，需要手动控制。为了配合即将到来的升级，所有脉冲EPR频率将具有相同的样品温度控制，从而最大限度地提高灵活性和吞吐量，跨越四个频段(每个光谱仪平台两个)：X-/Q-、Q-/S-和X-/L-频段，并指出Q和X频段是用户社区最需要的频率。人们对由EPR光谱监测的光激发样品的兴趣和使用有了很大的增加，这些样品主要由脉冲或瞬时EPR方法提供服务。像许多脉冲实验一样，数据收集可能很慢，而将脉冲光激励包含到微波(有时是射频)脉冲序列中会进一步延长测量时间。安装一台快速、高功率、可调谐的激光器将增加这些光学实验的容量和效率。与我们速度更慢、功率更低的可调谐激光相结合，EPR光谱仪将能够提供“双色”实验，人们对此也越来越感兴趣。冷却和光激发能力的扩展将为英国各地的NRF用户增加脉冲EPR的能力，包括ECR和博士生，新功能将扩大用户基础。如需联系国家EPR设施和服务，请发送电子邮件：epr@manchester.ac.uk，网址：https://www.chemistry.manchester.ac.uk/epr/。

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/