近日，瑞士洛桑联邦理工学院Giulia Tagliabue及其研究团队取得一项新进展。经过不懈努力，他们揭示了金晶体薄膜光致发光的量子力学效应。相关研究成果已于2024年4月19日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队成功揭示了单晶薄金箔片发光的量子力学效应。他们通过提出实验证据，并结合第一性原理模拟，证实了金箔片在带间区域激发时光致发光的起源，即电子与空穴复合的辐射发射。这一模型使得研究人员能够识别出，由于金膜厚度减少而引发的量子力学效应对金发光测量的影响。值得一提的是，这种效应在厚度仅为40nm的薄片发光信号中便可观察到，这主要归因于费米能级附近电子能带结构的面外离散性。

研究人员利用第一性原理建模定性地再现了观察结果，从而构建了对金单晶片发光的全面描述，为将其作为载流子动力学和光-物质相互作用探针，在材料科学中的广泛应用奠定了基础。此项研究为探索多种材料系统中的，热载流子和电荷转移动力学开辟了新的道路。

据悉，发光是探究金属热载子过程的重要途径，尤其在传感和能量应用中的等离激元纳米结构方面。然而，金属发光因性质较弱而鲜为人知，其微观起源颇具争议，其揭示纳米级载流子动力学潜力的部分仍有待发掘。

附：英文原文

Title: Quantum-mechanical effects in photoluminescence from thin crystalline gold films

Author: Bowman, Alan R., Rodrguez Echarri, Alvaro, Kiani, Fatemeh, Iyikanat, Fadil, Tsoulos, Ted V., Cox, Joel D., Sundararaman, Ravishankar, Garca de Abajo, F. Javier, Tagliabue, Giulia

Issue&Volume: 2024-04-19

Abstract: Luminescence constitutes a unique source of insight into hot carrier processes in metals, including those in plasmonic nanostructures used for sensing and energy applications. However, being weak in nature, metal luminescence remains poorly understood, its microscopic origin strongly debated, and its potential for unraveling nanoscale carrier dynamics largely unexploited. Here, we reveal quantum-mechanical effects in the luminescence emanating from thin monocrystalline gold flakes. Specifically, we present experimental evidence, supported by first-principles simulations, to demonstrate its photoluminescence origin (i.e., radiative emission from electron/hole recombination) when exciting in the interband regime. Our model allows us to identify changes to the measured gold luminescence due to quantum-mechanical effects as the gold film thickness is reduced. Excitingly, such effects are observable in the luminescence signal from flakes up to 40nm in thickness, associated with the out-of-plane discreteness of the electronic band structure near the Fermi level. We qualitatively reproduce the observations with first-principles modeling, thus establishing a unified description of luminescence in gold monocrystalline flakes and enabling its widespread application as a probe of carrier dynamics and light-matter interactions in this material. Our study paves the way for future explorations of hot carriers and charge-transfer dynamics in a multitude of material systems.

DOI: 10.1038/s41377-024-01408-2

Source: https://www.nature.com/articles/s41377-024-01408-2