Experimental study on T-2 relaxation time of protons in water suspensions of iron-oxide nanoparticles: Waiting time dependence

The T-2 relaxation time of protons in water suspensions of iron-oxide particle clusters is found to increase with the waiting time t(w) after the sample is inserted in the gap of the magnet with 1.41 T field, owing to field induced cluster aggregation. In order to compare the experimental results with existing theories, the measured T-2 has to be extrapolated to t(w) = 0, for which a power-law T-2 increment versus tw relation is proposed. The extrapolated T-2(0) is found to be inversely proportional to the volume fraction v of iron oxide. (C) 2009 Elsevier B.V. All rights reserved.