Magnetic resonance free induction decay in geological porous materials

Armin Afrough*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


Abstract: Magnetic resonance is an important noninvasive technology across life sciences and industry. Free induction decay is the simplest 1H magnetic resonance measurement method and an important means of probing fast-decaying signals in porous materials such as rocks, lung, and bone. It is commonly assumed that the free induction decay in geological porous materials is single-exponential. We experimentally observed two regimes of free induction decay behavior in geological porous materials: single-exponential and non-exponential decay. Numerical simulations that match experimental data highlight the effect of mass diffusion, especially in the single-exponential behavior. These two regimes of free induction decay in porous materials are associated with a bifurcation point in the solutions of the Bloch–Torrey equation for diffusion of fluids in confined domains in the presence of internal magnetic field gradients. This finding facilitates the extraction of absolute internal magnetic field gradient intensities from simple free induction decay measurements in the laboratory and field. This work also warns against common single-exponential assumptions in surface magnetic resonance methods employed in surveying underground water aquifers. Graphic Abstract: [Figure not available: see fulltext.].

Original languageEnglish
Article number107
JournalEuropean physical journal e
Issue number8
Number of pages7
Publication statusPublished - 2021


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