TY - JOUR A1 - Hartmann, Michael A1 - Mukamel, Shaul T1 - Femtosecond four wave mixing spectroscopy of conjugated polymers JF - The Journal of Chemical Physics N2 - Time‐resolved four wave mixing (4WM) signals of conjugated polymers are calculated using a density matrix approach and the Hartree–Fock approximation. The influence of the Coulomb interaction as well as size effects on the nonlinear optical response are examined. For the Hückel model (no Coulomb interaction), quantum beats due to the coherent excitation of several band states are found for small sizes, and photon echo‐like behavior is obtained for infinite size. The Coulomb interaction changes the nature of the response and gives rise to a broad delayed signal whose temporal profile is determined by the dephasing time. KW - Optical polymers KW - Dephasing KW - Band models Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5897 VL - 99 IS - 3 SP - 1597 EP - 1606 ER -