Strong nonradiative recombination of excitons in ${\mathrm{Cu}}_2\mathrm{O}$ and its impact on Bose-Einstein statistics

We have reproduced the spectroscopic evidence for Bose-Einstein statistics of excitons in ${\mathrm{Cu}}_2\mathrm{O}$ under a variety of conditions. However, our current measurements of the volume of the gas, its brightness, and the dependence of the energy distribution on crystal temperature, are inconsistent with a homogeneous gas of density sufficient to reach the quantum-statistical regime.