Ultrafast Nonlinear Microscopy in Nanowires and Nanowire Networks

在这个由化学系化学结构动力学和机制计划资助的项目中，北卡罗来纳大学教堂山分校的约翰·M·帕帕尼科拉斯教授将把泵浦-探测方法与非线性显微镜相结合，在超快时间尺度上研究一维纳米结构和网络中的电荷载流子动力学。该项目将开发一种新的显微技术，在一个空间位置激发纳米结构，并在另一个空间位置探测动力学，时间尺度从飞秒到纳秒不等。帕帕尼科拉斯教授和他的学生将使用这种空间分离的泵浦-探测显微镜来可视化电荷载流子在单个纳米棒和网络中的迁移。该项目将主要关注具有径向(即核壳)和轴向异质结的纳米线，目标是在载流子从一种材料移动到另一种材料时跟随载流子通过结构。该项目将研究尺寸和形状如何影响电荷载流子(电子和空穴)在单个纳米结构和相互连接的纳米结构集合中的流动。这个问题对于理解纳米科学和纳米技术中的许多问题是至关重要的。不同结构之间的行为差异，甚至同一结构内不同空间位置之间的行为差异，是复杂性的一个标志，它的存在对那些希望在设备应用中使用纳米材料的人构成了重大挑战。该项目还将在研究计划的背景下促进教学、培训和学习。研究生、本科生和高中生将参与这项研究。他们将开发技术先进的仪器，将这些方法应用于单一纳米结构的研究，并参与在国家会议上交流他们的结果。

In this project, funded by the Chemical Structure Dynamics and Mechanisms Program of the Chemistry Division, Prof. John M. Papanikolas of the University of North Carolina at Chapel Hill will combine pump-probe methodologies with nonlinear microscopy to investigate the charge carrier dynamics in one-dimensional nanostructures and networks on ultrafast time scales. The project will develop a new microscopy technique that will excite a nanostructure in one spatial location and probe the dynamics in another, on time scales ranging from femtoseconds to nanoseconds. Professor Papanikolas and his students will use this spatially-separated pump-probe microscope to visualize charge carrier migration through individual nanorods and networks. The project will focus primarily on nanowires with radial (i.e. core-shell) and axial heterojunctions with the goal of following carriers as the move through the structure, from one material to another.This project will investigate how size and shape influence the flow of charge carriers (electrons and holes) through both individual nanostructures and collections of interconnected nanostructures. This issue is fundamentally important and critical to understanding many problems in nanoscience and nanotechnology. Variation in behavior from structure-to-structure, and even between different spatial locations within the same structure, is a hallmark of complexity and its presence poses a major challenge to those wishing to use nanoscale materials in a device applications. The project will also promote teaching, training, and learning in the context of a research program. Graduate, undergraduate and high school students will participate in this research. They will develop the technologically sophisticated instrumentation, apply those methods to the study of single nanostructures, and take part in the communication of their results at national meetings.