非接触式原位多诊断核磁共振/介电谱
Non-contact in situ multi-diagnostic NMR/dielectric spectroscopy
AI总结：
本文提出一种利用NMR探头失谐量同时进行介电谱与NMR谱测量的非接触式原位多诊断方法，并通过醇类验证及沸石微孔中受限水研究证明其有效性。
摘要：
在核磁共振（NMR）探头中引入介电材料会改变探头电路的频率响应，这一现象通过探头的失谐得以显现。对于NMR谱学而言，这种失谐通常在进行NMR测量之前通过调谐和匹配探头来校正。探头失谐的幅度——即介电位移——可直接反映样品的介电性质，从而使NMR谱仪能够同时进行介电谱和NMR谱测量。通过测量样品介电常数随频率的变化，可以利用这一新方法进行介电常数谱分析。作为概念验证，使用商用CPMAS NMR探头对甲醇、乙醇、1-丙醇、1-戊醇和1-辛醇进行了评估。结果与标准介电谱技术收集的文献数据精确吻合。随后，该方法还被应用于研究限制在Si/Al比为11.5的MFI型亲水性沸石微孔中的水的溶剂-表面相互作用。在微孔中，水吸附在Brønsted酸位点和缺陷位点上，导致纳米受限水的介电常数急剧下降。利用带螺线管线圈的CPMAS探头有效电路模型，为这一新方法提供了理论背景，描述了介电样品插入探头后产生的失谐。
英文摘要：
Introduction of a dielectric material in an NMR probe head modifies the frequency response of the probe circuit, a phenomenon revealed by the detuning of the probe. For NMR spectroscopy, this detuning is corrected for by tuning and matching the probe head prior to the NMR measurement. The magnitude of the probe detuning - the dielectric shift - provides direct access to the dielectric properties of the sample, enabling NMR spectrometers to simultaneously perform both dielectric and NMR spectroscopy. By measuring sample permittivity as function of frequency, permittivity spectroscopy can be performed using the new methodology. As a proof concept, this was evaluated on methanol, ethanol, 1-propanol, 1-pentanol and 1-octanol using a commercial CPMAS NMR probe head. The results accurately match literature data collected by standard dielectric spectroscopy techniques. Subsequently, the method was also applied to investigate the solvent-surface interactions of water confined in the micropores of an MFI-type, hydrophilic zeolite with Si/Al ratio of 11.5. In the micropores, water adsorbs to Brønsted acid sites and defect sites, resulting in a drastically decreased dielectric permittivity of the nano-confined water. A theoretical background for the new methodology is provided using an effective electric circuit model of a CPMAS probe head with solenoid coil, describing the detuning resulting from insertion of dielectric samples in the probe head.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
