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arXiv · 1507.01398

Nuclear spin noise in NMR revisited

Guillaume Ferrand·Gaspard Huber·Michel Luong·Hervé Desvaux
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Abstract

The theoretical shapes of nuclear spin-noise spectra in NMR are derived by considering a receiver circuit with finite, preamplifier input impedance and a transmission line between the preamplifier and the probe. Using this model, it becomes possible to reproduce all observed experimental features: variation of the NMR resonance linewidth as a function of the transmission line phase, nuclear spin-noise signals appearing as a "bump" or as a "dip" superimposed on the average electronic noise level even for a spin system and probe at the same temperature, pure in-phase Lorentzian spin-noise signals exhibiting non-vanishing frequency shifts. Extensive comparison to experimental measurements validate the model predictions, and define the conditions for obtaining pure in-phase Lorentzian-shape nuclear spin noise with a vanishing frequency shift, in other words, the conditions for simultaneously obtaining the Spin-Noise and Frequency-Shift Tuning Optima.

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Guillaume Ferrand, Gaspard Huber, Michel Luong, Hervé Desvaux. 2015-07-06. Nuclear spin noise in NMR revisited. https://doi.org/10.1063/1.4929783

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