Longitudinal relaxation rate measurements for different signals unveiled by nutation spectroscopy: Application to the characterization of two arrangements experienced by water in a clay network,Magnetic Resonance in Chemistry

当前位置： X-MOL 学术 › Magn. Reson. Chem. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Longitudinal relaxation rate measurements for different signals unveiled by nutation spectroscopy: Application to the characterization of two arrangements experienced by water in a clay network
Magnetic Resonance in Chemistry ( IF 1.9 ) Pub Date : 2021-07-02 , DOI: 10.1002/mrc.5191
Maude Ferrari ₁ , Christian Moyne ₁ , Daniel Canet ₂

Affiliation

Nutation consists in monitoring the motion of nuclear magnetization under the application of a radiofrequency (rf) field. With an appropriate amplitude of the rf field, the nutation frequency depends on the NMR relaxation times. This property offers the possibility of differentiating species having the same Larmor frequency but differing by their relaxation times. This may occur for the composite proton NMR signal of water in complex systems. Separate nutation signals are thus observed with the possibility of measuring their longitudinal relaxation times by simply applying a saturation hard pulse, followed by an evolution interval, prior to the nutation sequence. This novel experiment has been used for studying the two sites existing for water in two kaolinite samples (one hydrated after stabilization of several months and the other nonhydrated). It turns out that water in these two sites differs essentially by its transverse relaxation time. Moreover, recovery is surprisingly biexponential for these two signals. A proper analysis of results obtained by this saturation-recovery nutation experiment provides not only the specific longitudinal relaxation rates of water in these two sites but also information about the averaging which occurs at long evolution times. This is discussed with regard of the structure and organization of the clay network. In particular, from relaxation rates at short evolution times, it is shown that this network is mainly constituted of ordered platelets, with a relatively weak proportion of randomly distributed platelets.

中文翻译：

章动光谱法揭示的不同信号的纵向弛豫率测量：应用于表征粘土网络中水经历的两种排列

章动包括在射频 (rf) 场的应用下监测核磁化的运动。在 rf 场幅度适当的情况下，章动频率取决于 NMR 弛豫时间。这种特性提供了区分具有相同拉莫尔频率但弛豫时间不同的物种的可能性。这可能发生在复杂系统中水的复合质子 NMR 信号中。因此，在章动序列之前，可以通过简单地应用饱和硬脉冲，然后是演化间隔来测量它们的纵向弛豫时间，从而观察到单独的章动信号。这项新颖的实验已用于研究两个高岭石样品（一个在稳定几个月后水合，另一个未水合）中存在的两个水位。事实证明，这两个位置的水在横向弛豫时间上有本质的不同。此外，这两个信号的恢复出人意料地是双指数的。对通过饱和恢复章动实验获得的结果进行适当分析不仅提供了这两个位置中水的特定纵向弛豫率，还提供了关于在长演化时间发生的平均的信息。这将在粘土网络的结构和组织方面进行讨论。特别是，从短演化时间的弛豫率来看，该网络主要由有序的血小板构成，随机分布的血小板比例相对较弱。令人惊讶的是，这两个信号的恢复是双指数的。对通过饱和恢复章动实验获得的结果进行适当分析不仅提供了这两个位置中水的特定纵向弛豫率，还提供了关于在长演化时间发生的平均的信息。这将在粘土网络的结构和组织方面进行讨论。特别是，从短演化时间的弛豫率来看，该网络主要由有序的血小板构成，随机分布的血小板比例相对较弱。令人惊讶的是，这两个信号的恢复是双指数的。对通过饱和恢复章动实验获得的结果进行适当分析不仅提供了这两个位置中水的特定纵向弛豫率，还提供了关于在长演化时间发生的平均的信息。这将在粘土网络的结构和组织方面进行讨论。特别是，从短演化时间的弛豫率来看，该网络主要由有序的血小板构成，随机分布的血小板比例相对较弱。对通过饱和恢复章动实验获得的结果进行适当分析不仅提供了这两个位置中水的特定纵向弛豫率，还提供了关于在长演化时间发生的平均的信息。这将在粘土网络的结构和组织方面进行讨论。特别是，从短演化时间的弛豫率来看，该网络主要由有序的血小板构成，随机分布的血小板比例相对较弱。对通过饱和恢复章动实验获得的结果进行适当分析不仅提供了这两个位置中水的特定纵向弛豫率，还提供了关于在长演化时间发生的平均的信息。这将在粘土网络的结构和组织方面进行讨论。特别是，从短演化时间的弛豫率来看，该网络主要由有序的血小板构成，随机分布的血小板比例相对较弱。

更新日期：2021-07-02

点击分享查看原文

点击收藏

阅读更多本刊最新论文本刊介绍/投稿指南11