NUCLEAR SPIN NOISE IN NMR REVISITED

Retour sur le Bruit de spin nucléaire en RMN

Guillaume Ferrand (1) , Gaspard Huber (2) , Michel Luong (1) , Hervé Desvaux (2)

1 DACM - Département des Accélérateurs, de Cryogénie et de Magnétisme (ex SACM)
2 LSDRM - Laboratoire Structure et Dynamique par Résonance Magnétique (LCF)

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.

Domains: Theoretical and/or physical chemistry; Chemical Physics [physics.chem-ph]; Analytical chemistry

Guillaume Ferrand, Gaspard Huber, Michel Luong, Hervé Desvaux. NUCLEAR SPIN NOISE IN NMR REVISITED. 2015. ⟨cea-01171610v2⟩