西藏谷露铯硅华~1H、^(29)Si魔角旋转核磁共振研究

~1H and ^(29)Si MAS NMR of the Geyserite in Tibetan Gulu Area,China

对谷露硅华样品进行固体MAS NMR分析,主要获得以下结论。1)采用1H MAS NMR技术,能分辨出谷露硅华不同类型的H2O或者OH-基团:孤立的内部羟基、氢键缔合羟基以及表面吸附的孔隙水和羟基结合水,其质子的化学位移分别为0.9×10-6、0.5×10-6、7.2×10-6、4.5×10-6和2.7×10-6。2)在硅华的1H→29Si CP/MAS NMR谱中可以看到,蛋白石中存在Q2结构,说明谷露硅华中存在与Q2硅配位的孪位羟基。3)从硅华的29Si MAS NMR实验结果可知,硅华的Cs含量与Q3的强度呈正相关关系,与Q4的强度呈负相关关系。由此可见,硅华中Cs的含量可能与蛋白石中的Q3(Q2)结构有关。

1H and 29Si MAS NMR were applied to analyzing the geyserite of Gulu Area. All these studies lead us to obtain the conclusions： 1 ） It is found that 1 H chemical shift values of isolated internal hydroxyls groups, strongly coupled external hydrogen bound silanols, pore water of surface adsorption and weakly coupled external H-bonded water are 0. 9×10-6 and 0. 5×10-6,7.2×10-6,4. 5 ×10-6,2. 7 ×10-6 ,re- spectively 2）According to 1H-29Si CP/MAS NMR spectra of the geyserite samples, this result elucidates the existence of geminal hydroxyl groups whithin the opal structures in the Gulu hot spring-type cesium deposit. 3）On the basis of 29Si MAS NMR spectra,from early to late stage ,the intensity of Q4 gradually falls while the intensity of Q3 rises. There is a positive correlation between the contents of Cs and the in- tensifies of Q3. so contents of Cs may be in relation to intensities of Q3 （ Q2 ）.