Suppression of radiation damping in high-resolution NMR.
The radiation damping field induced by an intense NMR line can be counterbalanced by a DANTE sequence of small flip angle pulses of opposite phase applied during the free induction decay. The transient NMR signal is acquired, one complex data point at a time, in the intervals between these DANTE pulses. As the intense signal decays, reducing the radiation damping field, the flip angles of the DANTE pulses are reduced at a matching rate. An experimental test on an aqueous solution of d-glucose demonstrates a reduction in linewidth at half height from 13.5 to 0.8 Hz, revealing a weak doublet response previously hidden under the broad water line.
Glucose↗