Figure 2
From: Exciton Relaxation Cascade in two-dimensional Transition Metal Dichalcogenides
Exciton formation and relaxation. Evolution of the momentum integrated exciton occupations Nμ(t). While the black line shows the overall number of incoherent excitons, the surface below the black line is divided into colored areas, whose surface ratio represents the relative fraction of the respective exciton state. After the optical excitation close to the single-particle band gap at t = 300 fs (yellow area) most electron-hole pairs occupy exciton states above the 2 s exciton. Those excited excitons decay into lower lying states via the emission of phonons and at approximately 1.5 ps a 1/e-fraction of the excited pairs has decayed into the 1s-ground state.
