A combined 17O RAPT and MQ-MAS NMR study of l-leucine

We report the application of rotor-assisted population transfer (RAPT) to measure the quadrupolar coupling constant (Cq) for spin 52 nuclei. Results from numerical simulations are presented on the magnitude of enhancement factor as a function of frequency offsets, i.e. the RAPT profile. Experimental O17 RAPT profile is traced for the amino acid l-leucine. In addition, results from MQ-MAS experiments are incorporated to determine the quadrupolar asymmetry parameter (ηq). Unlike previous reports, the O17 NMR parameters for an amino acid, l-leucine, is reported at a relatively low field of 9.4 T.