DYNAMICS OF SOLITONS AND POLARONS IN QUASI-ONE-DIMENSIONAL HALOGEN-BRIDGED MIXED-VALENCE COMPOUNDS

用光致吸收(PA)法研究了一维Peierls-Hubbard体系中电子-晶格耦合和链间相互作用对卤素桥联金属络合物(M=铂和X=Cl、Br或I)能隙状态的影响。在CDW幅度较小的络合物中，观察到三个PA带，分别为a1、a2和b。对链间相互作用不敏感的PA带a1和a2被指定为极化子。CDW的链间耦合作用减弱，形成带隙中带b，这与带电孤子有关，而在CDW幅值较大的络合物中，观察到具有较长寿命的两个PA带A和B。这些PA波段的光谱形状和激发轮廓与A1、A2和B波段的光谱形状和激发轮廓有很大不同。这些结果表明，能带态的产生过程和稳定能强烈地依赖于电子-晶格相互作用的大小。

The effects of the electron-lattice coupling and the interchain interaction on the gap states in the one-dimensional Peierls-Hubbard system have been investigated by the photo-induced absorption (PA) measurements of the halogen-bridged metal complexes (the MX chains ; M=Pt and X=Cl, Br or I). In the complexes having small amplitude of CDW,three PA bands named al, a2, and b are observed. The PA bands a1 and a2, which are insensitive to the interchain interation, are assigned to polarons. The decrease of the interchain coupling of CDW leads to a midgap band b, which is attributable to charged-solitons, While, in the complexes having large amplitude of CDW,there are observed the two PA bands A and B having the long life time. Spectral shapes and excitation profiles of these PA bands are considerebly different from those of the al, a2, and b bands. These results suggestthat generation processes and stabilization energies of the gap states are strongly dependent on the magnitude of electron-lattice interactions.