Decoupling, frequency swept

Fig. 7. Frequency-swept spin-decoupling experiments with methyl-3,4-dichloro-4-deoxy-a-D-g/yccro-pent-2-enopyranoside in deuterochloroform at 100 Mc./sec. (a), unperturbed resonance due to H4 (h), with irradiation of the low-field pair of lines of the H2 quartet (c), with irradiation of the low-field pair of lines of the Hj quartet. (From Coxon et al. )...

Fig. 1. iO. Natural abundance 13C NMR spectrum of acetone, neat liquid, (a) decoupled, 512 scans, (b) coupled, 4096 scans swept radio frequency 22.628 MHz corresponding to field strength of 2.13 Tesla the frequency differences relative to tetramethylsilane (TMS) are zh>c 3 = 655 IIz and... 

There are two basically different methods of spin decoupling field-sweep decoupling, in which the frequency difference between the decoupling field and the observing field is kept constant the spectrum is swept, and frequency-sweep decoupling, in which the value of H2, is kept constant as the value of Hi changes. The latter is more commonly used for routine studies and the results are easier to interpret. 

R.S. Thakur, N.D. Kurur, P.K. Madhu, Swept-frequency two-pidse phase modulation for heteronuclear dipolar decoupling in soHd-state NMR, Chem. Phys. Lett. 

One possible solution to achieving broadband inversion is to use swept-frequency adiabatic pulses, which give very high bandwidths in relation to the RF power used. These pulses are widely used in solution state experiments, for instance for facilitating heteronuclear decoupling, or in many applications in magnetic resonance imaging (MRI) [38]. 

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