Luminescence ofCu2O-Excitonic Molecules, or Not?

Luminescence spectra of ${\mathrm{Cu}}_2$O excited at various temperatures by a tunable dye laser showed no evidence of the existence of excitonic molecules (or biexcitons) as suggested recently by Gross and Kreingol'd. A pair of previously unreported peaks with an exceptionally strong temperature dependence has been observed below 3°K.