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中国物理学会期刊

α-LiIO3单晶中离子输运引起的高强度准弹性光散射

CSTR: 32037.14.aps.31.615

QUASI-ELASTIC STRONG LIGHT SCATTERING IN α-LiIO3 SINGLE CRYSTALS INDUCED BY IONIC TRANSPORTATION

CSTR: 32037.14.aps.31.615
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  • 激光束通过加c向直流电压的α-LiIO3单晶时,发生三种准弹性散射:散射光电位移矢量有特定取向且与入射光电位移矢量方向不一致者,散射光电位移矢量与入射光电位移矢量方向相同而散射带垂直c轴者以及散射光电位移矢量与入射光电位移矢量方向相同而散射带对c轴倾斜者,本文详细研究了这三种散射的空间频谱、精细结构、结构敏感性、弛豫规律以及光散射和晶体内电流密度与局部电场的关系,发现光散射发生于晶体内电流密度较大的区域,本文对三种散射的起因给予了说明:离子导体在直流电压作用下空间电荷的分布和运动引起

     

    The strong quasi-elastic scattering of light observed with a laser beam transmitting through an α-LiIO3 single crystal under the action of a DC field in the c-direction was further investigated. we recognized that the phenomenon consists of the following: (1) A scattering band appears perpendicular to the c-axis and extends to very large scattering angles. The scattered beam is the ordinary light, if the incident beam is the extraordinary light; and vice versa. If the incident beam contains both the ordinary and extraordinary components, two bands may be observed slightly separated in the azimuthal direction. (2) A band extends in the same direction as (1), but the polarization state does not change after scattering. (3) The scattered beam produces a pattern with one or a number of stripes in tilted directions other than those of c-axis. Their spatial frequency spectra are rather limited and the polarization state does not change. For all the three types of scattering we recorded the fine structure of intensity distribution vs the scattering angle, the relaxation of light scattering after the DC potential having been removed and the variation of the scattered intensity with the change of the locality through which the incident beam passes. Because of the behavior of unidimensional ionic conduction in α-LilO3, it is possible to prepare a specimen such that in a certain part of its volume the field is strong but no current flows. We noticed that no scattering occurs when the light passes through only such a space in a specimen. The strength of scattering is apparently associated with the current density. The scattering (1)-(3) may be interpreted as a radiation process of second order, phenomenologically described by the time and space fluctuation of the diagonal and nondiagonal components of the dielectric tensor. They are originated from the distribution and redistribution of the space charge. The nondiagonal components are now not zero even referred to the principal axes of the crystal. The fine structure of scattered intensity and related features should be attributed to the decoration of quasiperiodical defects.

     

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