Hasiuk Timothy, Jeffrey Kenneth R
Department of Physics, Guelph-Waterloo Physics Institute, University of Guelph, MacNaughton Building, Gordon Street, Guelph, Ontario, Canada N1G 2W1.
Solid State Nucl Magn Reson. 2008 Nov;34(4):228-39. doi: 10.1016/j.ssnmr.2008.09.003. Epub 2008 Oct 21.
In anticipation of using fluctuations in the nuclear dipolar and quadrupolar interaction as a probe of lithium ion motion in lithium borate glasses, the static values of these interactions were measured using a variety of echo techniques. The static quadrupolar echo spectrum of (7)Li and a calculation of the dipolar interaction in crystalline Li(2)B(4)O(7) (same chemical composition as the glass under study) were used to estimate the strength of the two interactions. These indicate that the dipolar and quadrupolar interactions for (6)Li will be of similar size and the dipolar interaction will be dominated by the unlike spin interaction between the (6)Li and the (10)B, (11)B spins. An appropriate theoretical model is proposed and explicit expressions for the echo amplitude are calculated in terms of the dipolar and quadrupolar second moments. This single spin model takes into account the quadrupolar interaction but treats the dipolar interaction as an effective magnetic field. Experimental results are presented which show the essential validity of the model and measurements lead to reasonable values for the dipolar and quadrupolar second moments. The relative merits of the various echo techniques are discussed.
为了利用核偶极和四极相互作用的波动作为硼酸锂玻璃中锂离子运动的探针，使用了多种回波技术来测量这些相互作用的静态值。利用(^{7}Li)的静态四极回波谱以及对晶体(Li_{2}B_{4}O_{7})（与所研究玻璃化学成分相同）中偶极相互作用的计算，来估计这两种相互作用的强度。这些结果表明，(^{6}Li)的偶极和四极相互作用大小相近，且偶极相互作用将由(^{6}Li)与(^{10}B)、(^{11}B)自旋之间的异自旋相互作用主导。提出了一个合适的理论模型，并根据偶极和四极二阶矩计算了回波幅度的显式表达式。这个单自旋模型考虑了四极相互作用，但将偶极相互作用视为有效磁场。给出的实验结果表明了该模型的基本有效性，测量得到了偶极和四极二阶矩的合理值。还讨论了各种回波技术的相对优点。
