Article

Applications of DNP-NMR for the measurement of heteronuclear T1 relaxation times.

Pfizer Global Research and Development, Sandwich Laboratories, Sandwich, Kent, UK.
Journal of Magnetic Resonance (impact factor: 2.14). 09/2007; 187(2):216-24. DOI:10.1016/j.jmr.2007.04.015 pp.216-24
Source: PubMed

ABSTRACT Measurement of heteronuclear spin-lattice relaxation times is hampered by both low natural abundance and low detection sensitivity. Combined with typically long relaxation times, this results in extended acquisition times which often renders the experiment impractical. Recently a variant of dynamic nuclear polarisation has been demonstrated in which enhanced nuclear spin polarisation, generated in the cryo-solid state, is transferred to the liquid state for detection. Combining this approach with small flip angle pulse trains, similar to the FLASH-T(1) imaging sequence, allows the rapid determination of spin-lattice relaxation times. In this paper we explore this method and its application to the measurement of T(1) for both carbon-13 and nitrogen-15 at natural abundance. The effects of RF inhomogeneity and the influence of proton decoupling in the context of this experiment are also investigated.

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Keywords

acquisition times
 
carbon-13
 
cryo-solid state
 
dynamic nuclear polarisation
 
enhanced nuclear
 
heteronuclear spin-lattice relaxation times
 
liquid state
 
low detection sensitivity
 
low natural abundance
 
natural abundance
 
polarisation
 
proton decoupling
 
rapid determination
 
renders
 
RF inhomogeneity
 
small flip angle pulse trains
 
spin-lattice relaxation times