Correlations between nuclear magnetic resonance based relaxation and diffusion-diffraction measurements in fluid-saturated isolated pores with relaxing surfaces are investigated. These correlations can be measured in two-dimensional experiments using previously reported pulse sequences that consist of an initial subsequence that probes diffusion-diffraction properties with pulsed gradient spin echo (PGSE), followed by another subsequence that measures relaxation effects. The magnetization is expressed in terms of diffusion eigenmodes of the restrictive geometry with the proper boundary condition. In general, each relaxation mode displays a different diffusion-diffraction behavior. For small values of the wave-vector q=γgδ (g is the pulsed gradient amplitude, and δ its time duration), an effective time dependent modal diffusion coefficient for each eigenmode is defined. In the fast-diffusion regime, in which surface relaxation is weak compared to diffusion across the pore, the lowest eigenmode dominates and the diffusion and relaxation dependencies of the magnetization approximately factorize. When surface relaxation is strong, higher eigenmodes contribute significantly and diffusion and relaxation effects cannot be factorized anymore. A correlation between the short-time modal diffusion coefficients and relaxation rates can be used to extract the properties of surface relaxation and the pore-size. The shift of the “diffraction” minima at q≈ integer multiples of 2π/ls (pore-size is ls) at weak relaxation values to higher wave-vectors at strong relaxation is associated with significant contributions from the higher modes to the magnetization at large wave vectors.