Many-Body Dynamics and Exciton Formation Studied by Time-Resolved   Photoluminescence
  The dynamics of exciton and electron-hole plasma populations is studied via time-resolved photoluminescence after nonresonant excitation. By comparing the peak emission at the exciton resonance with the emission of the continuum, it is possible to experimentally identify regimes where the emission originates predominantly from exciton and/or plasma populations. The results are supported by a microscopic theory which allows one to extract the fraction of bright excitons as a function of time. 
W. Hoyer, C. Ell, M. Kira, S.W. Koch, S. Chatterjee, S. Mosor, G.   Khitrova, H.M. Gibbs, and H. Stolz