MRI: Development of a broadband terahertz electron paramagnetic resonance spectrometer

MRI：宽带太赫兹电子顺磁共振波谱仪的研制

• 批准号: 1828570
• 负责人: Keith Nelson
• 金额: $ 52.85万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1828570&HistoricalAwards=false
• 关键词: MRI; Development; broadband; terahertz; electron

This award is supported by the Major Research Instrumentation, the Chemistry Research Instrumentation and the Chemical Measurements and Imaging programs. Professor Keith Nelson from MIT and colleague Robert Griffin have developed a broadband terahertz (THz) electron paramagnetic resonance (EPR) spectrometer. The terahertz energy is also known as submillimeter radiation, terahertz waves, which have an extremely high frequency that falls in between infrared radiation and microwave radiation in the electromagnetic spectrum. The new instrument is capable of measuring both linear-response EPR spectra and nonlinear EPR spectra including two-dimensional (2D) spectra. It uses an amplified femtosecond (one millionth of one billionth of a second) laser system and a 9.4 Tesla cryomagnet (a magnet that operates a low temperatures) to increase sensitivity. The measurements are conducted using THz fields that use a unique waveguide-based THz signal generation and readout platform. In general, an EPR spectrometer yields detailed information on the geometric and electronic structure of molecular and solid-state materials. It is also used to obtain information about the lifetimes of free radicals, short-lived, highly reactive species involved in valuable chemical transformations as well as the initiation of possible pathological growth. These studies impact many areas, from the synthesis of inorganic and organic molecules to the development of new solid-state materials to compounds of magnetic and biological interest. Employing examples inspired from ongoing research, this instrument is an integral part of research and teaching at the undergraduate and graduate levels at MIT. It is also used by researchers at many collaborating institutions such as the University of California at Berkeley and the University of California at Davis.The new spectrometer has capabilities not yet available in any commercially available instrument. This EPR spectrometer supports research using steady-state THz EPR spectroscopy of molecular magnets and time-resolved THz EPR spectroscopy of transition metal photochemistry (UC Berkeley) and zero-field and high-field THz EPR of metalloproteins. It is also used to test heterometallic oxido models for oxygen-evolution reaction catalysts (UC Davis) and for studying quantum spin liquid state. The new spectrometer is essential to evaluate compounds that provide information on fractional spin excitations in a 1D Ising chain, where Ising represents a mathematical model of ferromagnetism used in statistical mechanics that allows the identification of phase transitions.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.

该奖项得到了主要的研究工具，化学研究工具以及化学测量和成像计划的支持。 MIT的Keith Nelson教授和同事Robert Griffin开发了宽带Terahertz（THZ）电子顺磁共振（EPR）光谱仪。 Terahertz能量也称为亚毫升辐射，Terahertz波，其频率极高，在电磁频谱中的红外辐射和微波辐射之间。新仪器能够测量线性响应EPR光谱和非线性EPR光谱，包括二维（2D）光谱。它使用了扩增的飞秒（占十亿个秒的三分之一）激光系统和9.4 Tesla Cryomagnet（一种操作低温的磁铁）以提高灵敏度的激光系统。测量是使用使用基于波导的THZ信号生成和读出平台的THZ字段进行的。通常，EPR光谱仪得出有关分子和固态材料的几何和电子结构的详细信息。它还用于获取有关自由​​基的寿命，短寿命，高反应性的物种，涉及有价值的化学转化以及可能的病理生长的启动。这些研究影响了许多领域，从无机和有机分子的合成到开发新的固态材料到磁性和生物学兴趣的化合物。该工具采用了正在进行的研究启发的示例，是麻省理工学院本科和研究生级别的研究和教学的组成部分。许多合作机构的研究人员也使用了它，例如加利福尼亚大学伯克利分校和加利福尼亚大学戴维斯分校。新的光谱仪具有在任何商业上可用的工具中尚无功能。该EPR光谱仪支持分子磁体的稳态EPR光谱以及过渡金属光化学（UC Berkeley）和金属蛋白的零田和高田THZ EPR的时间分辨的THZ EPR光谱。它也用于测试氧气进化反应催化剂（UC Davis）和研究量子自旋液态态的杂氧模型。 The new spectrometer is essential to evaluate compounds that provide information on fractional spin excitations in a 1D Ising chain, where Ising represents a mathematical model of ferromagnetism used in statistical mechanics that allows the identification of phase transitions.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.