论文标题
关于所罗门在27个复杂铝氢化铝的NMR研究中的使用
On the use of Solomon echoes in 27Al NMR studies of complex aluminium hydrides
论文作者
论文摘要
四极耦合常数$ c_q $和不对称参数$η$已通过使用所罗门回声序列从$^{27} $ al nmr Spectra中确定了两个复杂的铝制氢化物，从$^{27} $ al nmr Spectra录制为固定样品。因此获得的KALH4（$ C_Q =（1.30 \ pm0.02）$ MHz，$η=（0.64 \ pm0.02）$）和naalh4（$ c_q =（3.11 \ pm0.02）$η<0.01 $）以前确定的数据一致。从静态光谱中确定这些参数的准确性至少与通过MAS方法一样好。将实验确定的参数（$δ_{ISO} $，$ c_q $和$η$）与从DFT-GIPAW（密度函数理论 - 量规能量预测的增强波）计算的参数进行了比较。除了GALH4的四极耦合常数外，Gipaw计算中高估了约30％，该协议非常好。讨论了所罗门回波序列在测量较不稳定材料或原位研究中的应用的优势。
The quadrupole coupling constant $C_Q$ and the asymmetry parameter $η$ have been determined for two complex aluminium hydrides from $^{27}$Al NMR spectra recorded for stationary samples by using the Solomon echo sequence. The thus obtained data for KAlH4 ($C_Q=(1.30\pm0.02)$ MHz, $η=(0.64\pm0.02)$) and NaAlH4 ($C_Q=(3.11\pm0.02)$ MHz, $η<0.01$) agree very well with data previously determined from MAS NMR spectra. The accuracy with which these parameters can be determined from static spectra turned out to be at least as good as via the MAS approach. The experimentally determined parameters ($δ_{iso}$, $C_Q$ and $η$) are compared with those obtained from DFT-GIPAW (density functional theory - gauge-including projected augmented wave) calculations. Except for the quadrupole coupling constant for KAlH4, which is overestimated in the GIPAW calculations by about 30%, the agreement is excellent. Advantages of the application of the Solomon echo sequence for the measurement of less stable materials or for in-situ studies are discussed.
