Experimental procedures are proposed and demonstrated that separate the spectroscopic contribution from both 47Ti and 49Ti in solid-state nuclear magnetic resonance spectra. These take advantage of the different nuclear spin quantum numbers of these nuclei that lead to different ‘effective’ radiofrequency fields for the central transition nutation frequencies when these nuclei occur in sites with a significant electric field gradient. Numerical simulations and solid-state NMR experiments were performed on the TiO2 polymorphs anatase and rutile. For anatase the separation of the two isotopes at high field (21.1 T) facilitated accurate determination of both EFG- and CSA-interactions using the different scaling of the EFG-tensor for the two isotopes. Rutile, having a larger quadrupolar coupling constant (CQ) was examined by 49Ti selective experiments at different magnetic fields to obtain spectra with different scalings of the two anisotropic tensors. A small chemical shielding anisotropy (CSA) of -30 ppm was determined.
Revised: April 7, 2011 |
Published: February 1, 2006
Citation
Larsen F.H., I.E. Farnan, and A.S. Lipton. 2006.Separation of 47Ti and 49Ti Solid-State NMR Lineshapes by Static QCPMG Experiments at Multiple Fields.Journal of Magnetic Resonance 178, no. 2:228-236.PNNL-SA-46388.