Magnetic susceptibility measurement by NMR: 1. The temperature dependence of TMS

• Published in: Journal of magnetic resonance (1997) 2020-03, Vol.312, p.106689-106689, Article 106689
• Main Author: Hoffman, Roy E.
• Format: Article
• Language: English
• Subjects: Chemical shift standard; Diamagnetism; Magnetic susceptibility
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2020.106689

[Display omitted] •Magnetic susceptibility is measured by an NMR spectrometer.•Accuracy of method is comparable to a susceptometer.•Variation of TMS chemical shift with temperature is measured.•Chemical shift of low pressure 3He is determined. Usually a dedicated susceptometer is needed to measure diamagnetism accurately. An NMR spectrometer is more readily available in most chemistry departments but till now has been inaccurate for measuring diamagnetism. An improved NMR method is introduced to measure the magnetic susceptibility, or diamagnetism with similar absolute accuracy as other methods. This is achieved by accurate modelling of the NMR sample shape and response profile of the probe. The new method is validated by comparing the measured diamagnetism of water against the literature standard to within 0.05%. As a first example of its application, the diamagnetism of CDCl3 was measured over a range of temperatures and used to reanalyze earlier measurements of the variation of the chemical shift of tetramethylsilane in CDCl3 against 3He gas. This improved on the accuracy and reliability of the result and will allow, for the first time, accurate studies of the absolute effect of temperature on chemical shift.