西藏谷露铯硅华1H、29Si魔角旋转核磁共振研究

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 of the Geyserite in Tibetan Gulu Area, China

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 ）.