Hot-exciton relaxation in ${\mathrm{Cd}}_{\mathit{x}}$${\mathrm{Zn}}_{1\mathrm{-}\mathit{x}}$Te/ZnTe multiple quantum wells

We have observed the creation of hot excitons at high momentum in ${\mathrm{Cd}}_{\mathit{x}}$${\mathrm{Zn}}_{1\mathrm{-}\mathit{x}}$Te multiple quantum wells and subsequent relaxation by LO-phonon emission to give sharp luminescence lines superimposed on a broader background. The difference between the exciton lifetime and dephasing time in these materials allows definite identification of the sharp lines as due to luminescence rather than resonant Raman scattering. The results are consistent with excitons localized in alloy potential fluctuations.