Ramankutty Krishnadas Kumaranchira, Yang Huayan, Baghdasaryan Ani, Teyssier Jeremie, Nicu Valentin Paul, Buergi Thomas
Département de Chimie Physique, Université de Genève, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
Phys Chem Chem Phys. 2022 Jun 8;24(22):13848-13859. doi: 10.1039/d1cp04708f.
We report distinct molecule-like and lattice (breathing) vibrational signatures of atomically precise, ligand-protected metal clusters using low-temperature Raman spectroscopy. Our measurements provide fingerprint Raman spectra of a series of noble metal clusters, namely, Au(SR), Ag(SR), AgAu(SR), Ag(SR) and Ag(SR) (-SR = alkyl/arylthiolate, -SR = dithiolate). Distinct, well-defined, low-frequency Raman bands of these clusters result from the vibrations of their metal cores whereas the higher-frequency bands reflect the structure of the metal-ligand interface. We observe a distinct breathing vibrational mode for each of these clusters. Detailed analyses of the bands are presented in the light of DFT calculations. These vibrational signatures change systematically when the metal atoms and/or the ligands are changed. Most importantly, our results show that the physical, lattice dynamics model alone cannot completely describe the vibrational properties of ligand-protected metal clusters. We show that low-frequency Raman spectroscopy is a powerful tool to understand the vibrational dynamics of atomically precise, molecule-like particles of other materials such as molecular nanocarbons, quantum dots, and perovskites.
我们利用低温拉曼光谱报告了原子精确、配体保护的金属簇独特的分子状和晶格（呼吸）振动特征。我们的测量提供了一系列贵金属簇的指纹拉曼光谱，即Au(SR)、Ag(SR)、AgAu(SR)、Ag(SR)和Ag(SR)（-SR = 烷基/芳基硫醇盐，-SR =二硫醇盐 )。这些簇独特且定义明确的低频拉曼带源于其金属核的振动，而高频带则反映了金属-配体界面的结构。我们观察到这些簇各自都有独特的呼吸振动模式。结合密度泛函理论计算对这些谱带进行了详细分析。当金属原子和/或配体发生变化时，这些振动特征会系统地改变。最重要的是，我们的结果表明，仅物理晶格动力学模型不能完全描述配体保护金属簇的振动特性。我们表明，低频拉曼光谱是理解其他材料如分子纳米碳、量子点和钙钛矿等原子精确、分子状粒子振动动力学的有力工具。
