The dipole response function of nuclear matter at zero and finite temperatures is investigated by employing the linearized version of the extended TDHF theory with a non-Markovian binary collision term. Calculations are carried out for nuclear dipole vibrations by employing the Steinwedel--Jensen model and compared with experimental results for ¹²⁰Sn and ²⁰⁸Pb.

PACS numbers: 21.60.Jz, 21.65.+f, 24.30.Cz, 25.70.Lm