Performances of the Lamb Model to Describe the Vibrations of Gold Quantum-Sized Clusters
Performances of the Lamb Model to Describe the Vibrations of Gold Quantum-Sized Clusters
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DOI：
10.1021/acs.jpcc.0c04722
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发表时间：
2020-09-03
影响因子：
3.7
通讯作者：
Margueritat, Jeremie
中科院分区：
文献类型：
--
作者：
Martinet, Quentin;Berthelot, Alice;Margueritat, Jeremie
兰姆模式描述了从恒星尺度到纳米尺度的物体整体振动。兰姆描述已建立从线性弹性理论，并考虑了均匀的弹性球。我们的工作试图通过研究有机分子稳定的量子尺寸的金团簇（Au-6，Au-9和Au-25）的振动来确定这种描述仍然有效的最小尺度。首先，我们的工作表明，通过低频拉曼光谱获得的小功能化的金团簇的实验频率可以用密度泛函理论计算来解释。此外，兰姆模型广泛成功地预测这些拉曼声学模式，只有当考虑周围的配体的质量的校正被添加。配体通过它们的质量以及它们与核的共价键影响核的振动模式。这种电子稳定的配体的意想不到的后果是兰姆描述的可持续性为小到六个原子的集群。最后，极限的兰姆模型可以达到在低温下的振动模式谱呈现出一个子结构的兰姆描述，开发一个均匀的球体，是无法预测的。
Lamb modes describe the vibrations of an object as a whole from the stellar scale to the nanometer one. Lamb description has been built from the linear elasticity theory and considers a homogeneous elastic sphere. Our work tries to determine the minimum scale where this description remains valid by studying the vibration of quantum-sized gold clusters (Au-6, Au-9, and Au-25) stabilized by organic molecules. First, our work shows that experimental frequencies of small-functionalized gold clusters obtained by low-frequency Raman spectroscopy can be interpreted with density functional theory calculations. Moreover, the Lamb model broadly succeeds in predicting these Raman acoustic modes only if a correction considering the mass of the surrounding ligands is added. Ligands affect vibrational modes of the core by their mass but also by their covalent bond with the core. The unexpected consequence of this electronic stabilization by the ligands is the sustainability of the Lamb description for clusters as small as six atoms. Finally, the limit of the Lamb model can be reached out at low temperature where the vibration mode spectrum presents a substructuration that the Lamb description, developed for a homogeneous sphere, is unable to predict.