基于法布里-珀罗谐振腔的W波段电子顺磁共振探头研制

doi:10.11938/cjmr20243111

摘要/Abstract

摘要：

本文研制了一种基于法布里-珀罗谐振腔的W波段电子顺磁共振探头．利用法布里-珀罗谐振腔所具备的大体积和开放腔等特点，本文将法布里-珀罗谐振腔用作谱仪探头的谐振器部分，并且设计了波纹波导来实现微波桥与法布里-珀罗谐振腔之间的低损耗微波信号传输．所研制的探头工作在W波段，空载品质因数为1 542．最终将该探头集成于W波段电子顺磁共振谱仪，通过测量Mn（II）掺杂的CaO粉末样品的谱线，展示了该探头在常温下用于W波段连续波电子顺磁共振实验的能力．探头的调制场频率设置为100 kHz，实验结果显示探头的最大调制场幅度可达8.9 G（1 G=10^-⁴ T），谱仪绝对自旋数灵敏度为6.6×10⁸spins/(G•$\sqrt{Hz}$)．

关键词: 电子顺磁共振, 法布里-珀罗谐振腔, 波纹波导, 灵敏度

Abstract:

This paper presents a new W-band electron paramagnetic resonance (EPR) probe design based on Fabry-Perot cavity. In this probe, a Fabry-Perot cavity with open structure and large effective volume is used as a resonator. Corrugated waveguides are designed to achieve low-loss microwave signal transmission between the W-band microwave bridge and the Fabry-Perot cavity. The probe works in W-band, and the unloaded quality factor is 1 542. A room-temperature continuous wave EPR experiment with Mn(II) in CaO powder was conducted after assembling the probe into a W-band EPR spectrometer. The results show that the modulation field amplitude is 8.9 G (1 G=10^-⁴ T) when the modulation field frequency is set to 100 kHz, and the absolute spin sensitivity is estimated to be 6.6×10⁸spins/(G•$\sqrt{Hz}$), which verifies the feasibility of utilizing Fabry-Perot cavity as a high sensitivity W-band EPR probe.

Key words: electron paramagnetic resonance (EPR), Fabry-Perot cavity, corrugated waveguide, sensitivity

中图分类号:

O482.53

罗文尤, 荣星. 基于法布里-珀罗谐振腔的W波段电子顺磁共振探头研制[J]. 波谱学杂志, 2024, 41(4): 393-404.

LUO Wenyou, RONG Xing. A W-Band Electron Paramagnetic Resonance Probe Based on Fabry-Perot Cavity[J]. Chinese Journal of Magnetic Resonance, 2024, 41(4): 393-404.

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名称	参数
样品	Mn标样品
温度	室温
微波功率	2.8 mW
时间常数	100 ms$({{f}_{\text{d}}}=0.78\text{ Hz)}$
调制场频率	100 kHz
调制场幅度	4.4 G
扫场范围	3.31~3.38 T
扫描点数	1750

序号	频率/GHz	探头种类	灵敏度/ （spins/(G•$\sqrt{Hz}$)）	极化度	室温灵敏度/ （spins/(G•$\sqrt{Hz}$)）
1^[34]	94	圆柱形谐振腔	$2.0\times 1{{0}^{7}}$@300 K	0.7515%	$2.0\times 1{{0}^{7}}$
2^[22]	95	法布里-珀罗谐振腔	$3.0\times 1{{0}^{8}}$@130 K	1.753%	$7.0\times 1{{0}^{8}}$
3^[35]	94	非谐振	$1.0\times 1{{0}^{9}}$@1.5 K	90.57%	$1.2\times 1{{0}^{11}}$
4（本工作）	94	法布里-珀罗谐振腔	$6.6\times 1{{0}^{8}}$@300 K	0.7515%	$6.6\times 1{{0}^{8}}$