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Summary form only given. Using picosecond photoluminescence (PL), we have investigated the temperature dependence of the radiative lifetime of the negatively charged exciton (X/sup -/) in CdTe quantum wells (QWs). The X/sup $/lifetime is found to increase from 70 ps at 2 K up to about 200 ps at 30 K. The increase is linear for temperatures bigger than 5 K and reveals that X/sup $/cannot be treated as a purely localised species. A linear increase is indeed predicted theoretically for delocalised X/sup -/. In addition, the observed temperature behaviour demonstrates that unlike the donor bound exciton to which X/sup -/ has been previously compared, X/sup -/ radiative recombination can take place with a specific strongly k dependent selection rule. The behaviour of X/sup -/ lifetime at the lower temperatures indicates the presence of a certain degree of localisation.