Nuclear resonance fluorescence experiments on ^{204, 206, 207, 208} Pb up to 6.75 MeV

Dipole and electric quadrupole excitations in ^{204, 206, 207, 208}Pb have been measured up to 6.75 MeV in resonant photon scattering experiments at the superconducting Darmstadt electron linear accelerator S-DALINAC using two Euroball-Cluster detector modules. In ²⁰⁸Pb, 14 excited states have been populated; in ²⁰⁶Pb, the decays of 41 states have been detected. Information about 45 heretofore unknown excited states in ²⁰⁴Pb could be measured as well as eleven known levels in ²⁰⁷Pb. The extracted dipole strength distributions are discussed within phenomenological ("pygmy resonance") and microscopic models (quasiparticle-phonon model). A strong fragmentation and a small shift of the detected E1 strength towards higher energies is observed with the opening of the neutron shell closure.