RELAXATION TIME MEASUREMT OF NITROXIDE PROBES FOR SCANNED-PROBE MAGNETIC FORCE

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 John Marohn开发了一种方法，将磁共振的超灵敏力梯度检测的适用性扩展到自旋晶格弛豫时间（T1）短至单个悬臂周期的样品。该方法依赖于检测悬臂梁频率或相位，其一般性通过在4.2 K和0.6 T下检测来自T1 = 1 ms氮氧自旋探针（TEMPAMINE）的薄膜中的电子自旋共振来证明。一个定制制造的悬臂与4 μ m直径的镍尖，用于实现磁共振灵敏度为410玻尔磁子在1 Hz的带宽。该实验的理论基础定量预测的线形和所观察到的悬臂梁频率偏移的幅度作为字段和悬臂梁样品分离的函数。新方法具有许多优点，使其非常适合于单个大分子中氮氧自旋标记的磁共振检测和成像，具有单自旋灵敏度

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. John Marohn has developed an approach that extends the applicability of ultrasensitive force gradient detection of magnetic resonance to samples with spin-lattice relaxation times (T1) as short as a single cantilever period. The generality of the approach, which relies on detecting either cantilever frequency or phase, was demonstrated by detecting electron spin resonance from a T1 = 1 ms nitroxide spin probe (TEMPAMINE) in a thin film at 4.2 K and 0.6 T. A custom fabricated cantilever with a 4 Mu m diameter nickel tip, was used to achieve a magnetic resonance sensitivity of 410 Bohr magnetons in a 1 Hz bandwidth. The theory underlying this experiment quantitatively predicts both the lineshape and the magnitude of the observed cantilever frequency shift as a function of field and cantilever-sample separation. The new approach has a number of advantages that make it well suited for magnetic resonance detection and imaging of nitroxide spin labels in an individual macromolecule at single-spin sensitivity