1H spin–lattice relaxation enhancement caused by magnetic core–shell nanoparticles—Testing theoretical models

Theoretical models of paramagnetic relaxation enhancement effects have been tested for 1H spin-lattice relaxation in water solutions of core-shell nanoparticles composed of NaDyF4 (core) and NaGdF4 (shell). The experimental data used for this testing have been collected in a broad frequency range, from 10 kHz to 400 MHz, vs temperature, for the core radius of the nanoparticles of 11 nm and the shell thicknesses of 0.55 and 1.3 nm. The models are based on a relatively simple description of the el