Wu Ian Y H, Jenkins Stephen J
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
Langmuir. 2022 Jun 14;38(23):7256-7271. doi: 10.1021/acs.langmuir.2c00740. Epub 2022 Jun 1.
The interaction of highly reactive species with solid surfaces can result in modes of adsorption quite distinct from the classic molecular and dissociative events that are usually thought to dominate. For instance, compelling experimental evidence suggests that adsorption of F at the Si{001} surface is often initiated by abstraction (and binding at the surface) of just one fluorine atom from the molecule; the second fluorine atom subsequently experiences either a separate atomic adsorption event or ejection from the surface altogether. Molecular dynamics simulations using empirical potentials support this concept but massively overestimate the prevalence of atomic ejection. In this work, we report first-principles molecular dynamics calculations that correctly show atomic ejection to be rare while providing insight into the details of abstractive adsorption. In addition, we also examine the case of F adsorption onto a monohydrogenated Si{001} surface, finding evidence for a different type of abstractive adsorption, in which a hydrogen atom may be removed from the surface to form a short-lived HFF intermediate. The latter rapidly decomposes to produce either HF or (via reaction with another surface hydrogen atom) H.
高活性物种与固体表面的相互作用可能导致吸附模式与通常认为占主导地位的经典分子和离解事件截然不同。例如，有令人信服的实验证据表明，氟在硅{001}表面的吸附通常是由从分子中仅提取一个氟原子（并结合在表面）引发的；第二个氟原子随后要么经历单独的原子吸附事件，要么完全从表面弹出。使用经验势的分子动力学模拟支持这一概念，但大幅高估了原子弹出的发生率。在这项工作中，我们报告了第一性原理分子动力学计算，该计算正确地表明原子弹出很少见，同时深入了解了抽象吸附的细节。此外，我们还研究了氟吸附到单氢化硅{001}表面的情况，发现了一种不同类型的抽象吸附的证据，其中一个氢原子可能从表面去除，形成一个短寿命的HFF中间体。后者迅速分解产生HF或（通过与另一个表面氢原子反应）H。
