GOALI: Advanced Cantilevers for MRFM with IBM Almaden

Sidles提出了一种重要的新成像技术，该技术可以精确地测量核磁共振（NMR）测量产生的力，从而对单个原子进行三维成像。电子纳米器件评估、基因测序、药物开发、存储介质分析以及许多其他商业、医疗和工业应用都将受益于这种新的成像技术。磁共振力显微镜（MRFM）的基本挑战在于必须检测的极小的力，这些力是数量级的阿牛顿（1an =10-18N）。机械悬臂梁的力检测灵敏度最终受到表现为力波动的热机械噪声的限制。为了达到MRFM所需的非常高的灵敏度，必须最小化悬臂的温度和刚度，同时最大限度地提高q。Rugar的IBM Almaden小组已经进行了数年的MRFM单原子成像研究，并取得了重大进展。最近的研究包括检测阿牛顿力的能力的演示，观察表面附近的许多fN-sale力，以及识别和减少用于检测这些力的悬臂中的热机械噪声机制的工作。所有这些都是在斯坦福大学和IBM之间由goali资助的合作中进行的，该合作以IBM的学生研究和斯坦福大学NNUN设施的使用为特色，制造了独特的悬臂。我们在这项更新工作中的目标集中在继续工作，以了解和减少限制Q值的微机械悬臂中的阻尼机制。我们已经构建了一个设备，可以系统地测量悬臂Q作为温度，尺寸和材料的函数，我们将使用它来确定阻尼机制。此外，我们建议开发一种新的微机械悬臂梁设计，允许在MRFM设备中进行原位退火。此外，我们还利用这些敏感的悬臂梁开发了一种新的表面耗散显微镜，其中悬臂梁上的捕获电荷诱导表面电荷，其迁移率可以在纳米尺度上确定。这三个方向的工作将继续进行。长期目标仍然是证明单原子的磁共振调频成像。

An important new imaging technique has been proposed by Sidles, in which forces derived from a Nuclear Magnetic Resonance (NMR) measurement would be measured accurately enough to allow 3-dimensional imaging of individual atoms. Electronic nanodevice evaluation, gene sequenceing, drug development, ananlysis of storage media, and many other commerical, medical and industrial applicatons would would benefit from this new imaging technology. The basic challenge of Magnetic Resonance Force Microscopy (MRFM) lies in the exceedingly small forces which must be detected, which are of order atto-newtons (1 aN=10-18N). Force detection sensitivity of mechanical cantilevers is ultimately limited by thermo-mechanical noise which apprears as a force fluctuation. To achieve the very high sensitivity required for MRFM, the temperature and stiffness of the cantilever must be minimized while maximizing Q. Research to obtain sngle-atom imaging by MRFM has been underway in Rugar's IBM Almaden group for several years, and significant progress has occurred. Recent research has included demonstrations of the ability to detect atto-newton forces, observation of numerous fN-sale forces near surfaces, and work to identify and reduce the mechanism for thermo-mechanical noise inthe cantilevers used to detect these forces. all of this has taken place during a GOALI-Funded collaboration between Standford and IBM, which has featured student research at IBM and use of NNUN facilities at Stanford to fabricate unique cantilevers. Our goals in this renewal effort focus on cntinued work to understand and reduce the damping mechanism in micromechanical cantilevers that limit the value of Q. We have constructed an apparatus which allows systematic experimental measurements of cantilever Q as a function of temperature, dimensions, and materials, and we will use this to identify damping mechanisms. Also we propose to develop a new design for a micromechanical cantilever that will allow in-situ annealing in the MRFM apparatus. In addition, we have used these sentisitve cantilevers to develop develop a novel surface dissipation microscopy, in which trapped charges on the cantilever induce surface charges whose mobility can be determined on the nm-scale. Work along all 3 of these directions will continue. The long-term goal remains the demonstration of MRFM imaging of sigle atoms.