Understanding the thermal response at short time scales in near-apex regions of a nanoprobe during ultrafast laser irradiation

本研究的目的是确定纳米探针近顶点区域在超快激光照射下的热响应。这是原子探针显微测量和光辅助扫描探针物质操作（纳米制造）的一个重要方面。目前的模型不能准确地预测温度。此外，确定探测器近尖端区域的精确温度受到实验验证模型预测能力的限制。智力优势：建模方法将采用麦克斯韦方程的解来获得探针尖端附近的光场分布。纳米探针内的能量传输将使用晶格玻尔兹曼方法和有限元技术相结合的方法来确定。由此产生的模型将提供关于纳米探针内部光强度分布的基本知识，以及近场激光加热如何以及在多大程度上影响探针温度。该模型的实验验证将通过激光辅助原子探针显微镜实验来实现。更广泛的影响：本研究涉及使用原子探针显微镜对材料进行原子尺度表征，以及涉及光辅助探针显微镜的一系列应用，包括但不限于纳米尺度生物、化学传感和纳米制造。本科和研究生教育将通过以下方式得到加强：(1)将研究成果纳入爱荷华州立大学教授的特定工程课程（扫描探针显微镜和纳米尺度热传输）；(2)与新生荣誉项目和学生勤工俭学项目合作，让本科生参与研究；(3)与美国女工程师学会（Society of women Engineers）共同指导和招收女学生；(4)通过美国国家科学基金会（NSF）校内国际材料研究所传播研究成果。

0932573SundararajanThe objective of the research is to determine the thermal response of the near-apex region of a nanoprobe in response to ultrafast laser irradiation. This is an important aspect of atom probe microscopy measurements and photo-assisted scanning probe matter manipulation (nanomanufacturing). Current models do not predict temperatures accurately. Furthermore, identifying exact temperatures in the near-tip region of the probe is limited by the ability to experimentally verify the model predictions. Intellectual Merit: The modeling approach will employ solutions of the Maxwell equation to obtain the optical field distribution in the vicinity of the probe tip. The energy transport within the nanoscale probe will be determined using a combined Lattice Boltzmann methodology and finite element technique. The resulting model will provide fundamental knowledge regarding the optical intensity distribution inside the nanoprobe as well as how, and to what extent the near-field laser heating affects probe temperatures. Experimental validation of the model will be achieved via laser assisted atom probe microscopy experiments.Broader Impacts: This research is relevant to atom-scale characterization of materials using atom probe microscopy as well as a range of applications involving photo-assisted probe microscopy including but not limited to nanoscale biological, chemical sensing, and nanomanufacturing. Undergraduate and graduate education will be enhanced by (1) incorporating the research results into specific engineering courses (Scanning Probe Microscopy and Nanoscale Thermal Transport) taught at Iowa State; (2) partnering with freshman honors and student work-study programs to involve undergraduate students in the research; (3) mentoring and recruiting women students in conjunction with the Society of Women Engineers and (4) dissemination of research results through an on-campus NSF International Materials Institute.