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Schematic diagram of sample region and detection coils. The NMR sample is contained in a vacuum cell, immersed in liquid helium, and is kept at room temperature with a heater. The helium Dewar sits in a single layer mu-metal shield with a closed end.
Frequency (and field) dependence of the NMR linewidth in water at . The solid line is a linear fit to the positive current data. The slope corresponds to a magnet inhomogeneity over the sample volume. The high frequency negative current data can be represented by this line shifted by (dashed line), where is determined by the residual environmental field gradient. A minimum linewidth of is observed at a finite frequency for negative currents, where the field gradient from the magnet opposes the residual gradient .
NMR signals from an oil/water mixture in a 4:1 mass ratio at (black curves) and (Gray). (a) Free induction decays and (b) lineshapes.
Temperature dependence of NMR linewidth and viscosity in Shell Vitrea 33 normalized to values. The NMR sample contained protons, as determined from the signal size.
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