Differential absorption spectroscopy shows a characteristic dependence on the density of 1s excitons in ${\mathrm{Cu}}_2\mathrm{O}$ at low temperature. The relation between absorption change and 1s exciton density is established and calibrated using one- and two-photon excitation. The calibrated density evaluation is applied to exciton transport measurements in a quasi-one-dimensional sample geometry. A numerical simulation of the transport yields extremely long exciton lifetimes of up to 3 ms. The Auger recombination of excitons is almost negligible, contrary to previous estimates. A deviation of the transport characteristics from the diffusive regime was not observed.

• Received 20 July 2001

DOI:https://doi.org/10.1103/PhysRevB.65.245209