摘要： Atomically thin Transition-metal dichalcogenides (TMDs) have come into the spotlight in optoelectronics thanks to their outstanding physical properties. In single-layer (1L) TMDs strong quantum confinement effects cause a weak screening of Coulomb, so that the excitons created by photo-excitation have large binding energy, up to several hundred meVs. While the steady-state properties of TMDCs have been studied in detail by linear optical techniques, the recent application of time-resolved nonlinear spectroscopy (mainly ultrafast pump-probe) has enabled the study of excited-state dynamics on femtosecond timescales opening up questions about the mechanisms of exciton relaxations and exciton-exciton interactions. Among TMDs, the spectrum of 1L MoS2 is characterized by two peaks of excitonic nature in the visible spectral region (1.9 eV and 2.05 eV), the so-called A and B excitons. They arise from optical transitions between the spin?orbit split top valence band and the bottom conduction band, around K and K’. Here we use two-dimensional electronic spectroscopy (2DES) to track the sub-ps excitonic interactions within 1L MoS2. We report 2DES measurements obtained on a chemical vapor deposition grown 1L MoS2 sample, at 77K, using sub 20-fs broadband pulses. Thanks to its unique combination of high temporal and spectral resolution, 2DES provides a series of excitation/detection correlation energy maps at different delays T, simultaneously covering the A and B excitons.