Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA.
Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
Phys Rev Lett. 2023 Jan 27;130(4):046202. doi: 10.1103/PhysRevLett.130.046202.
Using time- and angle-resolved photoemission, we present momentum- and energy-resolved measurements of exciton coupling in monolayer WS_{2}. We observe strong intravalley coupling between the B_{1s} exciton and A_{n>1} states. Our measurements indicate that the dominant valley depolarization mechanism conserves the exciton binding energy and momentum. While this conservation is consistent with Coulomb exchange-driven valley depolarization, we do not observe a momentum or energy dependence to the depolarization rate as would be expected for the exchange-based mechanism.
利用时间和角度分辨光发射，我们对单层 WS_{2}中的激子耦合进行了动量和能量分辨的测量。我们观察到 B_{1s}激子和 A_{n>1}态之间强烈的谷内耦合。我们的测量表明，主导的谷去极化机制保持了激子束缚能和动量。虽然这种守恒与库仑交换驱动的谷去极化一致，但我们没有观察到去极化率与动量或能量的依赖关系，这与基于交换的机制所预期的情况不符。
