Double-quantum NMR spectroscopy of 31P species submitted to very large CSAs.
We introduce an original pulse sequence, BR2(2)(1)(taupitau), which is a block super-cycled R2(2)(1) sequence employing as basic element a pi pulse sandwiched by 'window' intervals. This homonuclear dipolar recoupling method allows the efficient excitation of double-quantum coherences between spin-1/2 nuclei submitted to very large chemical shift anisotropy. We demonstrate that this technique can be employed in double-quantum<-->single-quantum (31)P homonuclear correlation experiment at high magnetic field (B(0)>or=14 T) and high MAS frequencies (nu(R)>or=30 kHz). The performances of BR2(2)(1)(taupitau) are compared to those of the double-quantum recoupling methods, such as BABA and bracketed fp-RFDR, which were already employed at fast MAS rates. The BR2(2)(1)(taupitau) sequence displays a higher robustness to CSA and offset than the other existing techniques.
Hu
B
B
UCCS, CNRS-8181, Lille-University, Villeneuve D'Ascq, France.
Delevoye
L
L
Lafon
O
O
Trébosc
J
J
Amoureux
J P
JP
D000465:Algorithms; D002250:Carbon Radioisotopes / Q000032:analysis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010759:Phosphorus Isotopes / Q000032:analysis* / Q000737:chemistry*; D011789:Quantum Theory
D002250:Carbon Radioisotopes; D010759:Phosphorus Isotopes