DEVELOPMENT OF PULSED ELECTRON NUCLEAR DOUBLE RESONANCE (ENDOR) AT 140 GHZ

我们开发了一台用于140 GHz脉冲Endor的光谱仪，这是 基于三个新的主单元，使用10.4T的磁铁 超导扫描线圈和~2H-核磁共振场锁系统，A 139.5 工作在四相容量的GHz微波桥 反射模式，EPR/核磁共振双共振探头。探测仪 由适用于射频辐射的TEOI I腔和 具有变量自动调谐能力的高品质谐振电路 射频照射。对于脉冲EPR，我们获得了90*脉冲 60-70 ns，在20K时的绝对灵敏度为3.109自旋/高斯。 利用脉冲Endor对光谱仪的性能进行了验证 标准双二苯基苯基烯丙基(BDPA)掺杂的光谱 聚苯乙烯和来自大肠杆菌核糖核苷酸的酪氨酸基 还原酶(RNR)。RNR酪氨酰基显示器的EPR谱 在5T时具有显著的g-各向异性，并用来证明 定向选择性戴维斯-恩多。

We developed a spectrometer for pulsed ENDOR at 140 GHz, which is based on three new main units a magnet utilizing a 1 0.4 T superconducting sweep coil and a 2 H-NMR field lock system, a 139.5 GHz microwave bridge with four phase capabilities operating in reflection mode, and a probe for EPR/NMR double resonance. The probe consists of a TEOI I cavity adapted for RF irradiation and a high-quality resonance circuit with autotuning capability for variable radio frequency irradiation. For pulsed EPR we obtain 90* pulses of 60 - 70 ns and an absolute sensitivity of 3.109 spins/Gauss at 20 K. The performance of the spectrometer was demonstrated with pulsed ENDOR spectra of a standard bis-diphenylene-phenyl-allyl (BDPA) doped into polystyrene and of the tyrosyl radical from E. coli Ribonucleotide Reductase (RNR). The EPR spectrum of the RNR tyrosyl radical displays substantial g-anisotropy at 5 T and was used to demonstrate orientation selective Davies-ENDOR.