1s-intraexcitonic dynamics in monolayer MoS2 probed by ultrafast mid-infrared spectroscopy

• DOI: 10.1038/ncomms10768
• Publication Date: 2016-02-25T10:30:00Z
• Authors: Soonyoung Cha; Ji Ho Sung; Sangwan Sim; Jun Park; Hoseok Heo; Moon-Ho Jo; Hyunyong Choi
• Keywords: Photoexcitation; Biexciton

Abstract The 1 s exciton—the ground state of a bound electron-hole pair—is central to understanding the photoresponse monolayer transition metal dichalcogenides. Above exciton, recent visible and near-infrared investigations have revealed that excited excitons are much richer, exhibiting series Rydberg-like states. A natural question is then how internal excitonic transitions interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands fundamentally different experimental tool capable probing optical from ‘bright’ np ‘dark’ Here we employ ultrafast mid-infrared spectroscopy explore in MoS 2 . We observed twofold →3 p within B →2 between excitons. Our results it takes about 0.7 ps for exciton reach quasi-equilibrium; characteristic time associated with rapid population transfer providing rich characteristics many-body dynamics two-dimensional materials.