ISSN:
0749-1581
Schlagwort(e):
superspin
;
BIRD pulses
;
spin dynamics
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The BIRD pulse sequence is widely used to distinguish between protons that are directly bonded to a 13C nucleus and those that are not. It consists of a proton 90° pulse, a delay of 1/(21JCH), simultaneous carbon and proton 180° pulses, a further delay of 1/2J and a final proton 90° pulse. For two spins at equilibrium, the effect of this sequence can be easily understood, but for complex systems the behaviour can be counter-intuitive. This paper explains the general behaviour of the BIRD sequence using theoretical equations and numerical simulations, and discusses some practical applications of the BIRD pulse train. The theoretical equations are derived using tables of general behaviour for the spin systems AX, AX2 and AX3. The tables allow the exact calculation of the effect of any pulse sequence on these spin systems, including all multiple quantum effects. The simulations show that the sequence is usually robust with respect to pulse imperfections and non-ideal spin systems. In other cases, particularly when signals should be suppressed, small errors can have dramatic consequences. The results derived here are for a BIRD sequence inserted into an INEPT experiment, but many of the conclusions can be applied to all of the more standard applications of the BIRD.
Zusätzliches Material:
9 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/mrc.1260330309
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