Wagner Joshua, Grabnic Tim, Sibener S J
The James Franck Institute and Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States.
J Phys Chem C Nanomater Interfaces. 2022 Nov 3;126(43):18333-18342. doi: 10.1021/acs.jpcc.2c05770. Epub 2022 Oct 19.
This paper examines the reactive surface dynamics of energy- and angle-selected N dissociation on a clean Ru(0001) surface. Presented herein are the first STM images of highly energetic N dissociation on terrace sites utilizing a novel UHV instrument that combines a supersonic molecular beam with an STM that is in-line with the molecular beam. Atomically resolved visualization of individual N dissociation events elucidates the fundamental reactive dynamics of the N/Ru(0001) system by providing a detailed understanding of the on-surface dissociation dynamics: the distance and angle between nitrogen atoms from the same dissociated N molecule, site specificity and coordination of binding on terrace sites, and the local evolution of surrounding nanoscopic areas. These properties are precisely measured over a range of impinging N kinetic energies and angles, revealing previously unattainable information about the energy dissipation channels that govern the reactivity of the system. The experimental results presented in this paper provide insight into the fundamental N dissociation mechanism that, in conjunction with ongoing theoretical modeling, will help determine the role of dynamical processes such as energy transfer to surface phonons and nonadiabatic excitation of electron-hole pairs (ehps). These results will not only help uncover the underlying chemistry and physics that give rise to the unique behavior of this activated dissociative chemisorption system but also represent an exciting approach to studying reaction dynamics by pairing the angstrom-level spatiotemporal resolution of an STM with nonequilibrium fluxes of reactive gases generated in a supersonic molecular beam to access highly activated chemical dynamics and observe the results of individual reaction events.
本文研究了在清洁的Ru(0001)表面上能量和角度选择的N解离的反应表面动力学。本文展示了利用一种新型超高真空仪器在台地位置上进行高能N解离的首批扫描隧道显微镜（STM）图像，该仪器将超音速分子束与与分子束同轴的STM相结合。对单个N解离事件的原子分辨可视化通过提供对表面解离动力学的详细理解，阐明了N/Ru(0001)系统的基本反应动力学：来自同一解离N分子的氮原子之间的距离和角度、台地位置上结合的位点特异性和配位情况，以及周围纳米区域的局部演化。在一系列入射N动能和角度范围内精确测量了这些性质，揭示了关于控制该系统反应性的能量耗散通道的此前无法获得的信息。本文给出的实验结果为基本的N解离机制提供了见解，结合正在进行的理论建模将有助于确定诸如能量转移到表面声子以及电子 - 空穴对（ehps）的非绝热激发等动力学过程的作用。这些结果不仅将有助于揭示导致这种活化解离化学吸附系统独特行为的潜在化学和物理过程，而且代表了一种令人兴奋的研究反应动力学的方法，即将STM埃级的时空分辨率与超音速分子束中产生的反应性气体的非平衡通量相结合以获取高度活化的化学动力学并观察单个反应事件的结果。
