Knowledge of the vibrational structure of a semiconductor is essential for explaining its optical and electronic properties and enabling optimized materials selection for optoelectronic devices. However, measurement of the vibrational density of states of nanomaterials is challenging. Here, using the example of colloidal nanocrystals (quantum dots), we show that the vibrational density of states of nanomaterials can be accurately and efficiently measured with inelastic X-ray scattering (IXS). Using IXS, we report the first experimental measurements of the vibrational density of states for lead sulfide nanocrystals with different halide-ion terminations and for CsPbBr₃ perovskite nanocrystals. IXS findings are supported with ab initio molecular dynamics simulations, which provide insight into the origin of the measured vibrational structure and the effect of nanocrystal surface. Our findings highlight the advantages of IXS compared to other methods for measuring the vibrational density of states of nanocrystals such as inelastic neutron scattering and Raman scattering.

中文翻译：

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用非弹性X射线散射测量基于纳米晶体的薄膜的振动密度

半导体振动结构的知识对于解释其光学和电子特性以及实现光电器件的最佳材料选择至关重要。然而，纳米材料状态的振动密度的测量是具有挑战性的。在这里，以胶体纳米晶体（量子点）为例，我们表明，利用非弹性X射线散射（IXS）可以准确有效地测量纳米材料状态的振动密度。使用IXS，我们报告了具有不同卤离子终端的硫化铅纳米晶体和CsPbBr ₃钙钛矿纳米晶体的态振动密度的首次实验测量。从头开始支持IXS发现分子动力学模拟，可以深入了解所测振动结构的起源以及纳米晶体表面的影响。我们的发现凸显了IXS与其他测量纳米晶体状态振动密度的方法（例如非弹性中子散射和拉曼散射）相比的优势。