Instantaneous Rayleigh-scattering from excitons localized in monolayer islands

Summary form only given. The emission dynamics of excitons in semiconductor quantum wells (QW) after a short-pulse excitation receives continued interest. A delayed secondary emission (SE) was noticed early on, unlike of what is observed in atomic vapors. We show that this difference is due to a uniform distribution of the excitonic oscillator strength in the QW plane. When exciting only a part of the resonance, the in-plane uniformity of the initially excited polarization is broken, and an instantaneous rise of the SE is observed.