@article{HartmannMukamel1993, author = {Hartmann, Michael and Mukamel, Shaul}, title = {Femtosecond four wave mixing spectroscopy of conjugated polymers}, series = {The Journal of Chemical Physics}, volume = {99}, journal = {The Journal of Chemical Physics}, number = {3}, url = {http://nbn-resolving.de/urn:nbn:de:0298-opus4-5897}, pages = {1597 -- 1606}, year = {1993}, abstract = {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 H{\"u}ckel 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.}, language = {en} }