Litman Yair, Bonafé Franco P, Akkoush Alaa, Appel Heiko, Rossi Mariana
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
MPI for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany.
J Phys Chem Lett. 2023 Aug 3;14(30):6850-6859. doi: 10.1021/acs.jpclett.3c01216. Epub 2023 Jul 24.
Tip-enhanced Raman scattering (TERS) has emerged as a powerful tool to obtain subnanometer spatial resolution fingerprints of atomic motion. Theoretical calculations that can simulate the Raman scattering process and provide an unambiguous interpretation of TERS images often rely on crude approximations of the local electric field. In this work, we present a novel and first-principles-based method to compute TERS images by combining Time Dependent Density Functional Theory (TD-DFT) and Density Functional Perturbation Theory (DFPT) to calculate Raman cross sections with realistic local fields. We present TERS results on free-standing benzene and C molecules, and on the TCNE molecule adsorbed on Ag(100). We demonstrate that chemical effects on chemisorbed molecules, often ignored in TERS simulations of larger systems, dramatically change the TERS images. This observation calls for the inclusion of chemical effects for predictive theory-experiment comparisons and an understanding of molecular motion at the nanoscale.
针尖增强拉曼散射（TERS）已成为获取原子运动亚纳米空间分辨率指纹图谱的强大工具。能够模拟拉曼散射过程并对TERS图像进行明确解释的理论计算通常依赖于对局部电场的粗略近似。在这项工作中，我们提出了一种基于第一性原理的新颖方法，通过结合含时密度泛函理论（TD-DFT）和密度泛函微扰理论（DFPT）来计算具有实际局部场的拉曼截面，从而计算TERS图像。我们展示了在自由苯和C分子以及吸附在Ag(100)上的TCNE分子上的TERS结果。我们证明，在较大系统的TERS模拟中常常被忽略的化学吸附分子上的化学效应，会显著改变TERS图像。这一观察结果要求在进行预测性理论与实验比较以及理解纳米尺度分子运动时考虑化学效应。
