Suppression of radiation damping in high-resolution NMR

The radiation damping held induced by an intense NMR line can be counterbal anced by a DANTE sequence of small flip angle pulses of opposite phase appl ied during the free induction decay. The transient NMR signal is acquired, one complex data point at a time, in the intervals between these DANTE puls es. As the intense signal decays, reducing the radiation damping held, the flip angles of the DANTE pulses are reduced at a matching rate. An experime ntal test on an aqueous solution of D-glucose demonstrates a reduction in l inewidth at half height from 13.5 to 0.8 Hz, revealing a weak doublet respo nse previously hidden under the broad water line. (C) 1999 Academic Press.