Power-optimized, time-reversal pulse sequence for a robust recovery of signals from rigid segments using time domain NMR

Author(s)

Garcia, Rodrigo H. S. ^[1] ; Filgueiras, Jefferson G. ^[2] ; deAzevedo, Eduardo R. ^[2] ; Colnago, Luiz Alberto ^[3]

Affiliation

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, CP 369, BR-13660970 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Inst Fis Sao Carlos, CP 369, BR-13660970 Sao Carlos, SP - Brazil

^[3] Embrapa Instrumentacao, Rua 15 Novembro, 1452, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: SOLID STATE NUCLEAR MAGNETIC RESONANCE; v. 104, DEC 2019.
• Web of Science Citations: 1

Abstract

Time domain NMR (TD-NMR) has been widely used on the analysis of liquids or liquid components in heterogeneous materials such as food, biological tissues, synthetic and bio polymers, oil-bearing rocks, biomasses and cement-based materials. The use of TD-NMR for studying solid and soft mater has been growing in number and variety of applications, mostly for organic systems where the detection of H-1 signals is highly advantageous. However, the strong H-1-H-1 dipolar interactions in solids make the H-1 FID to decay in the same order of the dead time of most commercially available NMR probe heads. Thus, solid echoes are often used for recovering signals from solid components. In this article we reinvestigate the time-reversal solid-echo pulse sequence proposed by Rhim and Kessemeier, seeking for optimal pulse power and timing conditions that maximize its efficiency on recovering H-1 signals from rigid segments. We show that under these optimized conditions, which we denote as Rhim and Kessemeier-Radiofrequency Optimized Solid-Echo (RK-ROSE), the experiment can be more efficient than its most popular counterparts Solid-Echo (SE) and mixed-Magic Sandwich Echoes (mixed-MSE). Our results also suggest that, despite the finite pulse power, with current probe technology the RK-ROSE experiment is potentially able to provide an accurate estimation of rigid components, without relying on an external calibration using multiple standard samples, as usually done in SFC analysis of the FID signal. At last, we demonstrate that RK-ROSE can be adapted as a simple filter to supress signals from mobile segments in heterogeneous materials. (AU)

• FAPESP's process: 17/02197-7 - Reaction monitoring of deuterated compounds synthesis, with use of metal catalysts, by NMR
• Grantee: Angel Rubén Higuera Padilla
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/24465-3 - NMR methods for plant cell wall characterization: development and applications to second generation biofuel technologies
• Grantee: Eduardo Ribeiro de Azevedo
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Regular Program Grants