Tracking the Photoinduced Dynamics of a Dark Excitonic State in Single-Layer WS_2 Via Resonant Autler-Townes Splitting

Excitons in monolayer transition metal dichalcogenides (1L-TMDs) exhibit a Rydberg-like series of bound states, including optically dark levels. Using a three-pulse scheme, we directly track the dynamics of the 2p dark exciton in 1L-WS_{2} through the Autler-Townes splitting of the bright 1s state. The splitting, induced by a midinfrared field resonant with the 1s-2p transition, reveals distinct 1s and 2p responses to photoexcitation. This approach provides new insight into many-body effects and offers a versatile experimental framework to probe driven excitonic dynamics in quantum materials.