PHTO-INDUCED PHASE TRANSITION AND ITS FORERUNNING PHENOMENON ON THE QUASI-ONE-DIMENSIONAL HALOGEN-BRIDGED TRANSITION METAL COMPOUNDS

用飞秒时间分辨荧光光谱研究了准一维卤素桥联铂配合物[Pt（en）_2][Pt（en）_2X_2][（ClO_4）_4（简称Pt-X，X=Cl，Br或I）的光激发态随时间的演化。在Pt-Br中，我们观察到了与自陷激子（STE）有关的绝热势阱中周期约为300 fs的波包振荡。STE具有约5.5ps的寿命。在Pt-Cl中，在STE发光带的低能量侧发现短寿命的热发光。振动弛豫在2 ps以内，STE的寿命为30 ps，解释了发光的整体行为。这些行为的发光再现的模型计算的基础上的波包传播的相互作用模式组成的频率色散体声子。在Pt-I中，STE发光衰减比Pt-Cl和Pt-Br中快得多（0.65 ps）。从观察到的STE寿命的依赖关系，它被认为是随着CT间隙能量的降低，势垒变得更低，和有效地产生的电荷孤子对的光激发在狭窄的CT间隙。特别是在Pt-I中，系统在热化之前似乎趋向于孤子对，如STE。新的准一维卤素桥联铂双核化合物，R_4[Pt_2（pop）_4l]（R=C_3H_7）_2NH_2）同时表现出压力和光致反应。我们发展了具有亚皮秒时间分辨率的光克尔门荧光光谱，光谱工具来研究超快弛豫过程。该系统的典型克尔效率和仪器响应函数分别为1.5%和1.250fs。应用该系统测量了ZnO中电子-空穴等离子体态的衰减。

The temporal evolution of photo-excited state in quasi-one-dimensional halogen-bridged platinum complexes [Pt(en)_2][Pt(en)_2X_2][(ClO_4)_4 (abbreviated as Pt-X, X=Cl, Br or I), has been comprehensively studied by femtosecond time-resolved luminescence spectroscopy. In Pt-Br, we have observed a wave-packet oscillation of a period of about 300fs in an adiabatic potential well associated with a self-trapped exciton (STE). The STE's have a lifetime of about 5.5 ps. In Pt-Cl, short-lived hot luminescence is found in the low energy side of a STE luminescence band. The overall behavior of luminescence is explained by the vibrational relaxation within 2 ps and the lifetime of the STE with 30 ps. These behaviors of luminescence are reproduced by a model calculation based on wavepacket propagation on an interaction mode composed of frequency-dispersed bulk phonons. In Pt-I, the STE luminescence decays much faster (0.65 ps) than those in Pt-Cl and Pt-Br. From the observed dependence of STE lifetime, it is supposed that the barrier becomes lower with decrease of the CT gap energy, and the charged-soliton pairs are efficiently produced by photoexcitation in narrow CT gap. In Pt-I, especially, the system seems to go toward the soliton pair before the thermalization as STE.New quasi-one-dimensional halogen-bridged platinum binuclear compound, R_4[Pt_2(pop)_4l](R=C_3H_7)_2NH_2) is found to show both the pressure- and photo-induced phase transitions at room temperature.We have developed the optical Kerr gate fluorescence spectroscopy with a subpicosecond time resolution as a new spectroscopic tool to investigate ultrafast relaxation processes. The typical Kerr efficiency and instrumental response function of the system are 〜5% and 〜250fs. This system is applied to measure the decay of electron-hole plasma state in ZnO.