Tang Xueyan, Suddarth Steven, Kantesaria Saurin, Garwood Michael
Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6(th) Street SE, Minneapolis, MN 55455, USA.
Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6(th) Street SE, Minneapolis, MN 55455, USA.
J Magn Reson. 2022 Sep;342:107279. doi: 10.1016/j.jmr.2022.107279. Epub 2022 Aug 1.
A frequency-swept longitudinal detection (LOD) EPR system is described for ultra-low field spectroscopy and relaxometry. With the capability of performing simultaneous transmit and receive with -80 dB isolation, this LOD-EPR can capture signals with decay constants in the nanosecond range and in theory even sub-nanosecond range, at fields close to the earth's magnetic field. The theoretical principles underlying this LOD-EPR are based on a fictitious field that accounts for the Z-axis magnetization polarized by a radiofrequency field alone. The electron spin relaxation time is obtained directly from a previously derived equation that describes the relationship between the relaxation time and the spectral peak position. Herein, the first frequency-swept LOD-EPR system is described in detail, along with experimental measurements of the short relaxation time (∼30 ns) of the free radical, 2,2-diphenyl-1-picrylhydrazyl, at zero to low field.
本文描述了一种用于超低场光谱学和弛豫测量的扫频纵向检测（LOD）电子顺磁共振（EPR）系统。该LOD-EPR能够以-80 dB的隔离度进行同时发射和接收，在接近地磁场的场强下，它可以捕获具有纳秒范围内甚至理论上亚纳秒范围内衰减常数的信号。这种LOD-EPR的理论原理基于一个虚拟场，该虚拟场考虑了仅由射频场极化的Z轴磁化强度。电子自旋弛豫时间直接从先前推导的一个方程中获得，该方程描述了弛豫时间与光谱峰值位置之间的关系。在此，详细描述了首个扫频LOD-EPR系统，以及在零场到低场下对自由基2,2-二苯基-1-苦基肼自由基的短弛豫时间（约30 ns）的实验测量结果。
