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H. Tachibana, M. Matsumoto, Y. Tokura, Y. Moritomo,A. Yamaguchi, S. Koshihara, R. D. Miller, and S. Abe
[Phys. Rev. B, Vol.47, pp.4363-4371, 1993]
Linear and nonlinear optical spectra (one-photon and two-photon absorption, photoluminescence, and electroabsorption spectra) have been investigated for solid thin films of polysilanes with a variety of conformations, such as trans-planar, alternating trans-gauche (TGTG'type), 7/3helical, and disordered backbone structures. Optical spectra have revealed features of one-dimensional exciton states characteristic of the respective conformations. In particular, the lowest allowed and second parity-forbidden (or two-photon allowed) transitions can be assigned to the ground (^{1}B_{1u}) and first excited (^{1}A_{g}) states of one-dimensional Wannier-type exciton, respectively. Furthermore, the higher excited exciton states and subsequent band-to-band transitions show up in the electroabsorption spectra for polysilanes with various conformations of the Si backbones. Quantitative analysis based on a microscopic theory for the one-dimensional excitons is also presented.