Understanding atomic force microscope nanomaterial synthesis: simulations and experiments

华盛顿大学的Marco Rolandi和Scott Dunham教授正在接受大分子，超分子和纳米化学计划的奖励，以探索实验和计算在空间上限制在原子力显微镜（AFM）尖端周围区域的纳米材料的合成。在纳米材料合成过程中，精确的位置控制对于器件集成以及在电子学和光电子学中的应用至关重要。原子力显微镜的尖端和样品之间的区域构成了一个独特的纳米级环境，在那里发生高度局部化的zeptomolar化学反应。最近的一种方法涉及在含有特设液体前体的尖端-样品间隙上施加中等（~10 V）偏压。 尖端样品接近将前体分子暴露于超过109 V/m的电场，以及电流密度高达107 A/m2的尖端场发射电子。这种策略已经证明了碳和半导体纳米线的空间限制合成，但对导致这些纳米材料的纳米级化学反应的清晰理解仍然缺乏。获奖项目的重点是通过创建基于物理的系统模型，了解纳米材料合成过程中尖端/样品间隙附近发生的基本过程。在这种集成的方法中，建模和实验工作协同进行，测量的行为表明可能的模型和用于改进表征的结果模型。这项工作的结果预计将奠定基础的战略，广泛适用于空间控制的纳米材料合成，使新的纳米器件设计。合成过程中缺乏空间控制是纳米材料和结构在纳米尺度上研究的公认瓶颈。该项目的简易纳米限制化学适用于广泛的材料，从而影响纳米科学和纳米材料技术应用的发展。从环境的角度来看，这种新颖的方法不需要使用大量的基于聚合物的牺牲层，也不需要用于光刻胶处理的数加仑水的污染，如在广泛采用的基于辐射的光刻中的情况。该项目的教育工作包括使更广泛的科学界（包括本科院校、社区学院、初中和高中）能够接触到纳米级科学和计算机建模。最新的实验结果和建模工具预计将被纳入本科和研究生课程。作为RET和REU现有计划的一部分，高中教师和本科生定期在纳米技术实验室中心举办。

Professors Marco Rolandi and Scott Dunham of the University of Washington are receiving an award from the Macromolecular, Supramolecular and Nanochemistry Program to explore both experimentally and computationally the synthesis of nanomaterials spatially confined in the region around the tip of an atomic force microscope (AFM). Accurate placement control during nanomaterial synthesis is critical for device integration and applications in electronics and optoelectronics. The region between the tip of an AFM and a sample constitutes a unique nanoscale environment where highly localized zeptomolar chemical reactions occur. A recent approach involves applying a moderate (~10 V) bias across the tip-sample gap containing ad-hoc liquid precursors. Tip sample proximity exposes the precursor molecules to electric fields in excess of 109 V/m, as well as tip field emitted electrons with current densities as high as 107 A/m2. This strategy has already demonstrated the spatially confined synthesis of carbon and semiconductor nanowires, but a clear understanding of the nanoscale chemical reactions leading to these nanomaterials is still lacking. The awarded project focuses on understanding the fundamental processes occurring near the tip/sample gap during nanomaterials synthesis by creating physically based models of the system. In this integrated approach, the modeling and experimental efforts proceed synergistically, with the measured behavior suggesting possible models and the resulting models used for refining the characterization. Results from this work are expected to lay the foundations for a strategy, broadly applicable to spatially controlled nanomaterial synthesis, that enables novel nanodevices design. Lack of spatial control in synthesis processes is a recognized bottleneck in the investigation of nanomaterials and structures at the nanometer scale. The facile nano-confined chemistry of this project is applicable to a broad range of materials, thus impacting nanoscale science and the development of nanomaterials technological applications. From the environmental standpoint, this novel approach does not require use of abundant quantities of polymer based sacrificial layers, nor the contamination of gallons of water for photoresist processing, as is the case in the widely adopted radiation-based lithography. Educational efforts in this project include making nanoscale science and computer modeling accessible to a broader scientific community including undergraduate institutions, community colleges, middle and high schools. The latest experimental results and modeling tools are projected to be included in courses at both the undergraduate and graduate levels. High school teachers and undergraduate students are routinely hosted at the Center for Nanotechnology laboratories, as part of the RET and REU existing programs.