Proceedings of the NMR USERS MEETING
PROCEEDINGS OF THE 19ᵗʰ NMR USERS MEETING - Vol.2 2023

1H Time Domain NMR (TD-NMR), based on benchtop spectrometers, has diverse applications in industrial and academic fields, as well as in industrial quality control and quality assurance. However, most of these analyzes are based on the characterization of liquids or liquid components of heterogeneous materials.
A major difficulty in TD-NMR experiments to characterize solid materials is the short-time decay of the 1H FID, which occurs in tenths of microseconds (~ 50 microseconds), i.e., in the same order as the dead time of most test heads commercially available NMR probe. This rapid decay is due to the strong homonuclear dipolar interaction between the 1H-1H spins as found in solid materials. For rigid materials it is necessary to use probes with short dead times or use solid echo sequences to intensify the signals from rigid components.
Thus, solid echoes are often used to recover signals from solid components. The aim of this study was to investigate the efficiency of the main echo sequences: Mixed-Magic Sandwich Echoes (mixed-MSE), Rhim and Kessemeier - Radiofrequency Optimized Solid-Echo (RK-ROSE) and Solid-Echo (SE). As a proof of principle, we acquire the polystyrene sample signals with the solid echo sequences at different spectrometer conditions (dead time and hard pulse settings). We will also show specific and general procedures to reliably reach the respective shape parameters (second momentum - M2).

[1] Garcia, Rodrigo HS, et al. "Power-optimized, time-reversal pulse sequence for a robust recovery of signals from rigid segments using time domain NMR." Solid State Nuclear Magnetic Resonance 104 (2019).