Jung Hyein, Dong Shuo, Zahn Daniela, Vasileiadis Thomas, Seiler Helene, Schneider Robert, Michaelis de Vasconcellos Steffen, Taylor Victoria C A, Bratschitsch Rudolf, Ernstorfer Ralph, Windsor Yoav William
Institute for Optics and Atomic Physics, Technical University Berlin, Strasse des 17, Juni 135, 10623 Berlin, Germany.
Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
Nano Lett. 2024 Oct 30;24(43):13671-13677. doi: 10.1021/acs.nanolett.4c03611. Epub 2024 Oct 21.
We study monolayer WSe using ultrafast electron diffraction. We introduce an approach to quantitatively extract atomic-site-specific information, providing an element-specific view of incoherent atomic vibrations following femtosecond excitation. Via differences between W and Se vibrations, we identify stages in the nonthermal evolution of the phonon population. Combined with a calculated phonon dispersion, this element specificity enables us to identify a long-lasting overpopulation of specific optical phonons and to interpret the stages as energy transfer processes between specific phonon groups. These results demonstrate the appeal of resolving element-specific vibrational information in the ultrafast time domain.
我们使用超快电子衍射研究单层二硒化钨。我们引入了一种方法来定量提取特定原子位点的信息，从而提供飞秒激发后非相干原子振动的元素特异性视图。通过钨和硒振动之间的差异，我们确定了声子群体非热演化的阶段。结合计算出的声子色散，这种元素特异性使我们能够识别特定光学声子的长期过量，并将这些阶段解释为特定声子群之间的能量转移过程。这些结果证明了在超快时域中解析元素特异性振动信息的吸引力。
