  We have studied the effect of disorder on the radiative properties of
semiconductor quantum wires by time-resolved photoluminescence spectroscopy.
The dependence of the radiative lifetimes is measured over a temperature range
extending from 8 to 150 K. At low temperatures we find that the measured
dependence does not conform to the theoretical prediction for recombination of
free excitons in a quasi one-dimensional system due to the major influence of
disorder. An extension of the theory is developped in order to take into
account exciton ionization and the contribution of free carriers. A mean
localization length for excitons is also estimated from the radiative lifetime
at 8 K.
