Spin scattering of 1S orthoexcitons in Cu2O

The interaction within the threefold degenerate Γ5+ 1S-orthoexciton of the yellow series in Cu2O leads to a population redistribution among the orthogonal states. We report new experiments which allow a more direct analysis of this process. The structure of the interaction is analyzed and the resulting selection rules are found to be in good agreement with the experiments. Furthermore, it is shown that propagation effects dominantly influence the population decay. This new analysis leads to different relaxation times as compared to previous results.