拉曼光谱
激子
声子
共振拉曼光谱
单层
共振(粒子物理)
拉曼散射
联轴节(管道)
相干反斯托克斯拉曼光谱
凝聚态物理
光谱学
分子物理学
自旋(空气动力学)
材料科学
化学
物理
原子物理学
纳米技术
光学
量子力学
热力学
冶金
作者
Elena del Corro,Andrés R. Botello-Mendez,Yannick Gillet,Ana Laura Elías,Humberto Terrones,Simin Feng,C. Fantini,Daniel Rhodes,Nihar Pradhan,Luis Balicas,Xavier Gonze,Jean Christophe Charlier,Mauricio Terrones,M. A. Pimenta
出处
期刊:Nano Letters
[American Chemical Society]
日期:2016-03-24
卷期号:16 (4): 2363-2368
被引量:115
标识
DOI:10.1021/acs.nanolett.5b05096
摘要
Resonant Raman spectroscopy is a powerful tool for providing information about excitons and exciton–phonon coupling in two-dimensional materials. We present here resonant Raman experiments of single-layered WS2 and WSe2 using more than 25 laser lines. The Raman excitation profiles of both materials show unexpected differences. All Raman features of WS2 monolayers are enhanced by the first-optical excitations (with an asymmetric response for the spin–orbit related XA and XB excitons), whereas Raman bands of WSe2 are not enhanced at XA/B energies. Such an intriguing phenomenon is addressed by DFT calculations and by solving the Bethe-Salpeter equation. These two materials are very similar. They prefer the same crystal arrangement, and their electronic structure is akin, with comparable spin–orbit coupling. However, we reveal that WS2 and WSe2 exhibit quite different exciton–phonon interactions. In this sense, we demonstrate that the interaction between XC and XA excitons with phonons explains the different Raman responses of WS2 and WSe2, and the absence of Raman enhancement for the WSe2 modes at XA/B energies. These results reveal unusual exciton–phonon interactions and open new avenues for understanding the two-dimensional materials physics, where weak interactions play a key role coupling different degrees of freedom (spin, optic, and electronic).
科研通智能强力驱动
Strongly Powered by AbleSci AI