Design and Implementation of Hyperdimensional Scanning Tunneling Microscopy

在化学系化学测量和成像(CMI)项目的支持下，加州大学圣地亚哥分校的李少伟正在开发一种方法，以测量在分子和二维材料中受到短激光脉冲激励时，电子运动和分子振动作为空间和时间函数的变化。这些低维系统表现出对纳米级化学变化敏感的独特动力学，而使用现有的微观技术很难观察到这些变化。Li团队正在开发一种名为超维扫描隧道显微镜(HD-STM)的新显微镜，以Angstrom空间分辨率和飞秒时间分辨率研究这些材料。这种方法有可能独一无二地揭示原子尺度超快动力学的细节，并有可能按需操纵这些动力学。李博士还将为高中生和本科生开发一个为期五周的暑期研究项目，重点是提高学生对科学的兴趣。超维扫描隧道显微镜(HD-STM)将STM与可见光红外泵浦频率、太赫兹(THz)探测频率和光学/光致发光光谱结合在一起，在广泛的空间、时间和频率范围内提取界面样品的结构、化学和反应细节。Li小组将致力于开发这种仪器，以便能够在空间、时间和频率域以高分辨率观察分子和低维材料中的电子转移和核运动。通过将高分辨率扫描隧道显微镜与光学光谱学相结合来进行高空间分辨率可见光泵浦太赫兹探测光谱学，有可能检查表面的化学结构和反应性，精确到单个原子或键，涉及广泛的科学领域。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry, Shaowei Li of the University of California, San Diego is developing a method to measure how electrons move and molecular vibrations change as a function of both space and time when excited by short laser pulses in molecules and two-dimensional materials. These low-dimensional systems exhibit unique dynamics that are sensitive to nanoscale chemical variations, which are difficult to observe using existing microscopic techniques. The Li group is developing a new microscopy called hyperdimensional scanning tunneling microscopy (HD-STM) to study these materials with Angstrom spatial resolution and femtosecond temporal resolution. This approach has the potential to uniquely reveal details about atomic-scale ultrafast dynamics and potentially enable the manipulation of these dynamics on-demand. Dr. Li will also develop a five-week summer research program for high school and undergraduate students that focuses on increasing student interest in science.Hyperdimensional scanning tunneling microscopy (HD-STM) couples STM with visible-infrared pump frequencies, THz (terahertz)-probe frequencies, and optical/photoluminescence spectroscopy to extract structure, chemical, and reactivity details about interfacial samples across a wide scale of space, time, and frequency. The Li group will work to develop this instrumentation so that electron transfer and nuclear motion in molecules and low-dimensional materials can be observed with high resolution in the space, time, and frequency domains. By coupling high resolution STM with optical spectroscopy to do high spatial resolution visible-pump THz-probe spectroscopy, there is the potential to examine chemical structure and reactivity at surfaces down to a single atom or bond, with implications for a broad range of science.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.