论文标题
WSE $ _2 $单层中低温语音子侧带的时间演变
Temporal evolution of low-temperature phonon sidebands in WSe$_2$ monolayers
论文作者
论文摘要
HBN封装的单层单层钨液（WSE $ _2 $）的低温光致发光（PL）显示出在明亮的激子以下的众多尖锐的发射峰。他们中的一些人最近被确定为动量黑暗状态的声子边带。但是，尚未透露这些边带出现背后的激子动态。在这项联合理论实验研究中，我们从理论上预测并在实验上观察到时间分辨的PL，为光激发后形成的热激体的热激体提供了微观见解。在理论和实验之间良好的一致性，我们在数十秒钟的时间范围内展示了声子侧带的频谱红移，反映了动量黑暗状态下热激子的热激体热力化的热量。此外，我们预测瞬态PL中消失的瞬态声子边带的出现。所获得的微观见解适用于具有多个激子山谷的广泛的2D材料。
Low-temperature photoluminescence (PL) of hBN-encapsulated monolayer tungsten diselenide (WSe$_2$) shows a multitude of sharp emission peaks below the bright exciton. Some of them have been recently identified as phonon sidebands of momentum-dark states. However, the exciton dynamics behind the emergence of these sidebands has not been revealed yet. In this joint theory-experiment study, we theoretically predict and experimentally observe time-resolved PL providing microscopic insights into thermalization of hot excitons formed after optical excitation. In good agreement between theory and experiment, we demonstrate a spectral red-shift of phonon sidebands on a timescale of tens of picoseconds reflecting the phonon-driven thermalization of hot excitons in momentum-dark states. Furthermore, we predict the emergence of a transient phonon sideband that vanishes in the stationary PL. The obtained microscopic insights are applicable to a broad class of 2D materials with multiple exciton valleys.
