Huang Shin-Jong, Liu Shang-Bin, Chan Jerry C C
Department of Chemistry, National Taiwan University, No. 1 Section 4 Roosevelt Road, Taipei 106, Taiwan, ROC.
Solid State Nucl Magn Reson. 2009 Oct;36(2):110-7. doi: 10.1016/j.ssnmr.2009.07.002. Epub 2009 Aug 5.
An experimental method for the heteronuclear dipolar recoupling of half-integer quadrupole nuclei is proposed. The idea is to manipulate the central transition based on the recoupling technique of spin-polarization-inversion rotary resonance. This method allows the extraction of structural parameters under fast magic-angle spinning. Its validity has been examined by the average Hamiltonian theory and numerical simulations. The initial rotational-echo dephasing arising from the dipolar evolution can be approximated by a parabolic function, from which the heteronuclear van Vleck second moment can be estimated. A factor, estimated from two-spin simulations, is required to account for the effects of the quadrupolar coupling and is rather independent of the geometry and the orders of the spin systems. Our method can facilitate the structural characterization of materials containing half-integer quadrupole nuclei under high-resolution condition. Experimental verification has been carried out on two aluminophosphate systems, namely, AlPO(4)-5 and AlPO(4)-11.
提出了一种用于半整数四极核异核偶极重耦合的实验方法。其思路是基于自旋极化反转旋转共振的重耦合技术来操纵中心跃迁。该方法允许在快速魔角旋转下提取结构参数。通过平均哈密顿量理论和数值模拟检验了其有效性。由偶极演化引起的初始旋转回波去相可以用抛物线函数近似，由此可以估计异核范弗莱克二阶矩。需要根据双自旋模拟估计一个因子来考虑四极耦合的影响，且该因子与自旋系统的几何结构和阶数相当无关。我们的方法有助于在高分辨率条件下对含半整数四极核的材料进行结构表征。已在两种磷酸铝体系，即AlPO(4)-5和AlPO(4)-11上进行了实验验证。
