MRI: Development of an Agile Free-Electron-Laser-Powered Pulsed Electron Magnetic Resonance (FEL-EMR) Spectrometer

MRI：开发敏捷自由电子激光驱动脉冲电子磁共振 (FEL-EMR) 能谱仪

• 批准号: 2117994
• 负责人: Mark Sherwin
• 金额: $ 216万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2117994&HistoricalAwards=false
• 关键词: MRI; Development; Agile; Free; Electron

Non-Technical Description:Excitation and detection of the magnetic response of electrons at high magnetic fields -- high-field electron magnetic resonance (EMR) -- is needed for breakthroughs in disciplines ranging from biology to quantum information science. All magnetic resonance spectrometers are based on the fact that the building blocks of matter -- protons, most atomic nuclei, and electrons --behave like tiny magnets whose strength is quantified by their magnetic moments. Magnetic resonance imaging (MRI) spectrometers deployed in many hospitals excite and detect the magnetic moments of protons in large magnetic fields using powerful pulses of electromagnetic radiation at frequencies well below 1 GHz. Because the magnetic moments of electrons are nearly 700 times larger than those of protons, high-field EMR spectrometers must use powerful pulses of electromagnetic radiation with frequencies above 100 GHz, or 0.1 THz. Due to the extreme difficulty of generating such powerful, high-frequency pulses, the capabilities of high-field EMR spectrometers lag far behind those of MRI and other nuclear magnetic resonance spectrometers. In this project, researchers at the University of California at Santa Barbara leverage their unique sources of powerful sub-THz electromagnetic radiation to build an agile free-electron-laser-powered EMR spectrometer. This spectrometer is designed to enable unprecedented studies of the basic properties of candidates for new classes of quantum sensors; fast, energy-efficient alternatives to electronics; and exotic quantum mechanical states of matter. The diverse team of undergraduates, graduate students, and post-doctoral researchers receive unique training in developing state-of-the-art scientific instrumentation, which is excellent preparation for the science and engineering workforce.Technical Description:The free-electron lasers (FELs) at the University of California at Santa Barbara are unique sources of powerful, quasi-continuous wave sub-THz and THz electromagnetic radiation. A new helical FEL in combination with "pulse slicing" technology delivers pulses with peak powers of about 10 kW at frequencies that are tunable between 140 and 500 GHz. The FEL-powered EMR (FEL-EMR) spectrometer, supported by this Major Research Instrumentation project, is designed to rotate spin-1/2 species by 90 degrees in a few nanoseconds at magnetic fields up to 16.5 Tesla and sample temperatures between 1.6 and 300 K, enabling rapid electron spin manipulation and read-out in paramagnetic, antiferromagnetic, and strongly correlated spin systems. The scientific targets of the FEL-EMR spectrometer include the optimization of paramagnetic contrast agents for dynamic nuclear polarization-enhanced nuclear magnetic resonance of proteins; the measurement of spin coherence in optically addressable molecular qubits; the investigation of damping and spin transport in antiferromagnetic spintronics; and searches for elusive excitations of fractionalized magnets.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述：从生物学到量子信息科学等学科的突破都需要高磁场下电子磁响应的激发和检测——高场电子磁共振（EMR）。所有磁共振波谱仪都基于这样一个事实：物质的组成部分——质子、大多数原子核和电子——的行为就像微小的磁铁，其强度通过磁矩来量化。许多医院部署的磁共振成像 (MRI) 光谱仪使用频率远低于 1 GHz 的强大电磁辐射脉冲来激发和检测大磁场中的质子磁矩。由于电子的磁矩比质子的磁矩大近 700 倍，因此高场 EMR 波谱仪必须使用频率高于 100 GHz（即 0.1 THz）的强大电磁辐射脉冲。由于产生如此强大的高频脉冲极其困难，高场EMR波谱仪的能力远远落后于MRI和其他核磁共振波谱仪。在该项目中，加州大学圣塔芭芭拉分校的研究人员利用其独特的强大亚太赫兹电磁辐射源来构建敏捷的自由电子激光驱动的 EMR 光谱仪。该光谱仪旨在对新型量子传感器候选者的基本特性进行前所未有的研究；快速、节能的电子产品替代品；和奇异的物质量子力学状态。由本科生、研究生和博士后研究人员组成的多元化团队接受了开发最先进科学仪器的独特培训，这为科学和工程人员做好了极好的准备。技术说明：自由电子激光器（FEL） ）位于加州大学圣塔芭芭拉分校，是强大的准连续波亚太赫兹和太赫兹电磁辐射的独特来源。新型螺旋 FEL 与“脉冲切片”技术相结合，可在 140 至 500 GHz 之间可调的频率下提供峰值功率约为 10 kW 的脉冲。由 FEL 供电的 EMR (FEL-EMR) 光谱仪由该重大研究仪器项目支持，旨在在高达 16.5 特斯拉的磁场和 1.6 至 1.6 之间的样品温度下，在几纳秒内将自旋 1/2 物质旋转 90 度。 300 K，可在顺磁、反铁磁和强相关自旋系统中实现快速电子自旋操纵和读出。 FEL-EMR波谱仪的科学目标包括优化用于蛋白质动态核极化增强核磁共振的顺磁造影剂；光学可寻址分子量子位中自旋相干性的测量；反铁磁自旋电子学中阻尼和自旋输运的研究；该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。