We demonstrate an unexpected decay-recovery behaviour in the time-dependent 1H NMR relaxation times of water confined within a hydrating porous material. Our observations are rationalised by considering the combined effects of decreasing material pore size and evolving interfacial chemistry, which facilitate a transition between surface-limited and diffusion-limited relaxation regimes. Such behaviour necessitates the realisation of temporally evolving surface relaxivity, highlighting potential caveats in the classical interpretation of NMR relaxation data obtained from complex porous systems.
@article{arxiv.2210.06016,
title = {NMR surface relaxivity in a time-dependent porous system},
author = {Neil Robinson and Razyq Nasharuddin and Einar O. Fridjonsson and Michael L. Johns},
journal= {arXiv preprint arXiv:2210.06016},
year = {2023}
}