用红外吸收光谱确定层状硅酸盐中羟基键的方向

层状硅酸盐样品用于红外二色性研究,当射线的电场矢量与振动的偶极矩方向成一角度时,这吸收与角度成比例,当某振动的偶极矩与电场矢量平行时,产生最大吸收,而这两矢量彼此垂直时将不产生吸收。在云母和有关晶体中可看到,在二八面体组成中,在改变电场矢量时倾斜OH团的OH振动强度保持不变,而与在三八面体组成中垂直于解理面方向的八面体OH团相比,当层状定向颗粒方向改变时显示强度大大增加,由此能获得层状硅酸盐OH键的方向,在晶体结构分析中能提供有价值的信息。

IAS DETERMINATION OF THE ORIENTATION OF OH-BOND AXIS IN LAYER SILICATES

Samples of layer silicates have been selected for infrared dichroic study. When the electric vector of radiation makes an angle with the direction of transition moment of vibration, the absorption is proportional to the angle. Thus, the maximum absorption occurs when the transition moment of certain vibration and the electric vector are parallel. Zero absorption will occur when the two vectors are perpendicular to each other. In micas and related crystals, it is observed that the intensity of OH vibration of the inclined OH groups in the dioctahedral compositions remains unchanged with the variation of the electric vector. In contrast with those perpendicular to the cleavage plane-oriented octahedral OH groups in the trioctahedral compositions, a large increase is shown in intensity when the direction of the lamellae-oriented particles changes. From this can be obtained the orientation of OH-bond axis in layer silicates, from which some valuable information can be developed on crystal structure analyses.