Figure 2. Resolving different physical environments of molecules.

(a) Schematics of the sample consisting of porous silica gel 60 powder immersed in water (1% H₂O in D₂O). (b) Experimental ultrafast D–T₂ data after the Fourier transform in the spatial frequency dimension. The first row (red) is shown on the top along with the coil sensitivity profile (black). (c) Ultrafast D–T₂ map including one peak arising from water in the pores (D=0.74·10⁻⁹ m² s⁻¹, T₂=29 ms) and the other from water between the particles (D=1.9·10⁻⁹ m² s⁻¹, T₂=87 ms). The map is the result of a 2D Laplace inversion of experimental data corrected using the coil sensitivity profile in the region affected by the frequency-swept pulse (z=0.96–1.99 cm). (d) Corresponding reference map obtained in the conventional D–T₂ correlation experiment. The experiments were carried out at 300 MHz ¹H frequency. The total time in the conventional experiment was 46 min, using eight scans per increment, while only 2 min 30 s were required with a total of 32 scans in the ultrafast experiment.