Sequence for simultaneous measurement of long-limit diffusion and longitudinal relaxation in unilateral NMR | Nouvelle séquence pour la mesure simultanée du coefficient de diffusion et du temps de relaxation longitudinal par RMN unilatérale
2019
Sucre, O. | Rondeau-Mouro, Corinne, C. | Optimisation des procédés en Agriculture, Agroalimentaire et Environnement (UR OPAALE) ; Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA) | UNIV BRETAGNE LOIRE FRA ; Partenaires IRSTEA ; Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
[Notes_IRSTEA]Article Number: UNSP 106619 [Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]SPEE [ADD1_IRSTEA]Sûreté alimentaire
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Mostrar más [+] Menos [-]Inglés. Under unilateral NMR with large gradients (20 T/m) and in samples with long values of spin-lattice relaxation time T1 (>2000 ms) and of large coefficient of diffusion (2*10-6 mm2/ms), measurement of T1 by classical sequences becomes affected by the Brownian movement of spins. By taking it into account, a modified saturation sequence called GAUSS-SR has been proposed that permits to carry out direct measurement of both D and T1 under the conditions mentioned. Evolution of z component of the magnetization Mz is thus the main phenomena to model. The sequence is composed of three main parts: i) a saturation train tailored to render the Mz profile in Gaussian shape, ii) a main delay whereby the simultaneous effect of T1 and Diffusion on this profile has been analytically solved and iii) an detection train to acquire the signal with good signal-to-noise ratio. The sequence was implemented in a NMR-MOUSE, allowing to achieve the aimed measurement. Due to its reliance on the coherence imposed over the longitudinal and not over the transversal component of the magnetization, the sequence succeeds in providing the long-limit value of the diffusion coefficient.
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