Understanding atomic force microscope nanomaterial synthesis: simulations and experiments

华盛顿大学的Marco Rolandi教授和Scott Dunham教授正在接受大分子、超分子和纳米化学计划的奖励，他们将从实验和计算两方面探索空间限制在原子力显微镜(AFM)尖端区域的纳米材料的合成。在纳米材料合成过程中，精确的布局控制对于器件集成和在电子学和光电子学中的应用至关重要。原子力显微镜尖端和样品之间的区域构成了一个独特的纳米级环境，在这里发生了高度局域化的零分子化学反应。最近的一种方法涉及在含有特殊液体前体的针尖-样品间隙上施加适度(~10V)的偏压。TIP样品的邻近使前体分子暴露在超过109V/m的电场中，以及TIP场发射的电流密度高达107A/m2的电子。这一策略已经证明了碳和半导体纳米线的空间受限合成，但对导致这些纳米材料的纳米级化学反应仍然缺乏清楚的了解。获奖项目的重点是通过创建基于物理的系统模型来了解纳米材料合成过程中针尖/样品缝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，测量的行为建议可能的模型和结果模型用于完善表征。这项工作的结果有望为一种广泛适用于空间控制纳米材料合成的战略奠定基础，该战略能够实现新的纳米设备设计。在纳米尺度的纳米材料和结构的研究中，缺乏对合成过程的空间控制是公认的瓶颈。该项目的简便纳米受限化学适用于广泛的材料，从而影响了纳米科学和纳米材料技术应用的发展。从环境的角度来看，这种新的方法不需要使用大量的基于聚合物的牺牲层，也不需要像广泛采用的基于辐射的光刻技术那样在光致抗蚀剂处理过程中污染数加仑的水。该项目的教育努力包括使更广泛的科学界，包括本科生机构、社区大学、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纳入本科生和研究生的课程。作为RET和REU现有计划的一部分，高中教师和本科生经常在纳米技术实验室中心接受接待。

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.