High-field Dynamic Nuclear Polarization using Spin Probes and Intrinsic Defects at Local Interfaces of Polymers and Solids

使用自旋探针的高场动态核极化和聚合物和固体局部界面的固有缺陷

• 批准号: 1112572
• 负责人: Song-I Han
• 金额: $ 46.5万
• 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: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1112572&HistoricalAwards=false
• 关键词: field; Dynamic; Nuclear; Polarization; using

With support from the Chemical Measurement and Imaging program in the Division of Chemistry, Prof. Song-I Han and her group at the University of California - Santa Barbara are developing new instrumentation and methodologies for high magnetic field nuclear magnetic resonance (NMR) to probe the detailed microstructure of complex and heterogeneous materials, e.g. of multiphase block copolymers or amorphous silicon. The sensitivity of conventional NMR spectroscopy is insufficient to probe the microstructural properties at the surface or interface at the necessary sub-nanometer length scale. Prof. Han addresses this challenge by developing novel dynamic nuclear polarization (DNP)-amplified NMR instrumentation and methods at 7 Tesla that enhance signals by up to five orders of magnitudes through cryogenic cooling and polarization transfer from polarized electron spins to nuclear spins. A unique and crucial aspect of the approach is utilization of strategic electron spin probes specifically located through chemical functionalization, or intrinsic paramagnetic defects that are critical to the function or malfunction of the materials. Prof. Han is adding concurrent continuous wave and pulsed electron paramagnetic resonance (EPR) detection capabilities to a home-built spectrometer to provide complete materials characterization through the nuclear and electron spin probes. The high field DNP approach may have high impact on the study of a wide range of functional and heterogeneous materials, e.g. a variety of multiphase polymer systems or amorphous and crystalline Si based photovoltaic materials, whose interfacial properties or intrinsic paramagnetic centers lie at the core of their function or malfunction. Educational impact is enhanced by provision of research opportunities for undergraduate students and by supporting professional development for women scientists pursuing high level science careers.

在化学系化学测量和成像项目的支持下，加州大学圣巴巴拉分校的Song-I Han教授和她的团队正在开发用于高磁场核磁共振（NMR）的新仪器和方法，以探测复杂和异质材料的详细微观结构，例如多相嵌段共聚物或非晶硅。常规NMR光谱的灵敏度不足以在必要的亚纳米长度尺度下探测表面或界面处的微观结构性质。Han教授通过开发新型动态核极化（DNP）放大NMR仪器和方法来应对这一挑战，这些仪器和方法在7特斯拉下通过低温冷却和从极化电子自旋到核自旋的极化转移将信号增强高达五个数量级。该方法的一个独特和关键的方面是利用战略电子自旋探针，特别是通过化学功能化，或内在的顺磁性缺陷，是至关重要的功能或故障的材料。Han教授正在为自制的光谱仪添加同时连续波和脉冲电子顺磁共振（EPR）检测功能，以通过核和电子自旋探针提供完整的材料表征。高场DNP方法可以对广泛的功能和非均质材料的研究具有高度影响，例如各种多相聚合物系统或基于无定形和结晶Si的光伏材料，其界面性质或固有顺磁中心位于其功能或故障的核心。通过为本科生提供研究机会和支持追求高水平科学事业的女科学家的专业发展，增强了教育影响。