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

ABSTRACT: The 1s exciton--the ground state of a bound electron-hole pair--is central to understanding the photoresponse of monolayer transition metal dichalcogenides. Above the 1s exciton, recent visible and near-infrared investigations have revealed that the excited excitons are much richer, exhibiting a series of Rydberg-like states. A natural question is then how the internal excitonic transitions are interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands a fundamentally different experimental tool capable of probing optical transitions from 1s 'bright' to np 'dark' states. Here we employ ultrafast mid-infrared spectroscopy to explore the 1s intraexcitonic transitions in monolayer MoS2. We observed twofold 1s?3p intraexcitonic transitions within the A and B excitons and 1s?2p transition between the A and B excitons. Our results revealed that it takes about 0.7?ps for the 1s A exciton to reach quasi-equilibrium; a characteristic time that is associated with a rapid population transfer from the 1s B exciton, providing rich characteristics of many-body exciton dynamics in two-dimensional materials.

SUBMITTER: Cha S

PROVIDER: S-EPMC4773417 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

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

Cha Soonyoung S Sung Ji Ho JH Sim Sangwan S Park Jun J Heo Hoseok H Jo Moon-Ho MH Choi Hyunyong H

Nature communications 20160225

The 1s exciton--the ground state of a bound electron-hole pair--is central to understanding the photoresponse of monolayer transition metal dichalcogenides. Above the 1s exciton, recent visible and near-infrared investigations have revealed that the excited excitons are much richer, exhibiting a series of Rydberg-like states. A natural question is then how the internal excitonic transitions are interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands a fundam ...[more]

PMID: 26911982

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

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

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