Excited states of one-dimensional excitons in polysilanes as investigated by two-photon spectroscopy

Two-photon-absorption spectra have been investigated for solid films of polysilanes with various Si-backbone conformations such as trans planar, alternating trans-gauche, helical, and disordered forms. In all the polysilanes with ordered backbones, the distinct two-photon-absorption peaks were observed at energies 0.8 1.0 eV above the one-photon-absorption peaks. These one-photon and two-photon transitions are interpreted in terms of the ground and excited states of one-dimensional excitons on the Si backbones. © 1991 The American Physical Society.