Yao Xiaolong, Lee Yeonghun, Ceresoli Davide, Cho Kyeongjae
Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, United States.
CNR-SCITEC, Istituto di Scienze e Tecnologie Chimiche "G. Natta", via Golgi 19, 20133 Milan, Italy.
J Phys Chem A. 2021 Jun 3;125(21):4524-4533. doi: 10.1021/acs.jpca.0c11309. Epub 2021 May 21.
A quantitative study on inelastic electron scattering with a molecule is of significant importance for understanding the essential mechanisms of electron-induced gas-phase and surface chemical reactions in their excited electronic states. A key issue to be addressed is the quantitatively detailed inelastic electron collision processes with a realistic molecular target, associated with electron excitation that leads to potential ionization and dissociation reactions of the molecule. Using the real-time time-dependent density functional theory (TDDFT) modeling, we present quantitative findings on the energy transfers and internal excitations for the low energy (up to 270 eV) electron wave packet impact with the molecular target cobalt tricarbonyl nitrosyl (CTN, Co(CO)NO) that is used as a precursor in electron-enhanced atomic layer deposition (EE-ALD) growth of Co films. Our modeling shows the quantitative dependence of the wave packet sizes, target molecule orientations, and impact parameters on the energy transfer in this inelastic electron scattering process. It is found that the wave packet sizes have little effect on the overall profile of the internal multiple excited states, whereas different target orientations can cause significantly different internal excited states. To evaluate the quantitative prediction capability, the inelastic scattering cross-section of a hydrogen atom is calculated and compared with the experimental data, leading to a constant scaling factor over the whole energy range. The present study demonstrates the remarkable potential of TDDFT for simulating the inelastic electron scattering process, which provides critical information for future exploration of electronic excitations in a wide range of electron-induced chemical reactions in current technological applications.
对分子进行非弹性电子散射的定量研究对于理解电子诱导的气相和表面化学反应在其激发电子态下的基本机制具有重要意义。需要解决的一个关键问题是与实际分子靶发生的定量详细的非弹性电子碰撞过程，这与导致分子潜在电离和解离反应的电子激发相关。利用实时含时密度泛函理论（TDDFT）建模，我们给出了低能（高达270 eV）电子波包与分子靶三羰基亚硝酰钴（CTN，Co(CO)NO）碰撞时能量转移和内部激发的定量结果，CTN用作钴膜电子增强原子层沉积（EE-ALD）生长中的前驱体。我们的建模显示了波包大小、靶分子取向和碰撞参数对这种非弹性电子散射过程中能量转移的定量依赖性。结果发现，波包大小对内部多重激发态的整体轮廓影响很小，而不同的靶取向会导致显著不同的内部激发态。为了评估定量预测能力，计算了氢原子的非弹性散射截面并与实验数据进行比较，在整个能量范围内得到一个恒定的比例因子。本研究证明了TDDFT在模拟非弹性电子散射过程方面的巨大潜力，这为当前技术应用中广泛的电子诱导化学反应中电子激发的未来探索提供了关键信息。
