The origin of the Stokes shift: The line shapes of quantum well exciton absorption and photoluminescence spectra

We present a model of exciton absorption and emission line shapes which predicts, inter alia, a linear relation between the absorption line width, Γ, and the Stokes shift, Δ, between the photoluminescence and the absorption peak energies: Δ = 0.6Γ. This prediction agrees very well with experimental results over two orders of magnitude.