POLARONS AND SOLITONS IN HALOGEN-BRIDGED PLATINUM COMPLEXES

The halogen-bridged mixed-valence transition metal complexes have a doubly degenerate linear chain structure, 

As above mentioned, the displacement of halogen atoms from the midpoints between neighbouring metal ions brings on the doubly degeneracy, that is, the Peierls state, in the chain, so that the breathing mode of halogen 

Both solitons and polarons have their characteristic absorption bands below the band gap energy. Then, for the identification of the nonlinear excited states, the optical absorption and the electron spin resonance spectra must be studied, to get information about the midgap states and the spin, respectively. Studies of the electrical properties are also needed to get information about the charge. In this report, the excited states in single crystals of (Pt(en)2][Pt(en) ] 2 4 are studied by the experimental methods mentioned above, and the photo-induced excited state in this material is shown to be polarons, which are also produced by halogen-doping. 

The absorption spectra were measured by a double pass method. The sample ina ass vessel was fixed in the optical system during photo-excitation or halogen-doping so that the experimental configuration was kept in same condition and the sample was not exposed to air. 

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POLARONS AND SOLITONS IN HALOGEN-BRIDGED PLATINUM COMPLEXES EFFECTS OF PHOTOEXCITATION AND HALOGEN-DOPING ON OPTICAL ABSORPTION AND ESR SPECTRA... 

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