th  - 1987 - 51st ENC Conference

WK22 - POSTERS
SOLVENT SUPPRESSION WITHOUT PHASE DISTORTION
Malcolm H. levitt* and Hazy F. Roberts
M.I.T., NN14-5122, Cambridge, MA 02139
Ve describe a new class of pulse sequences, NERO (Non-linear Excitation
Rejecting On-Resonance), which alloy wideband excitation of an NI~
spectrum except for a deep, flat section near the carrier vhere the
response is zero. The novel feature of the nev sequences is that phase
distortion of excited resonances is negligible, in contrast to usual
methods based on linear response. Ve rill shov numerical simulations
and experimental results for the following sequence, called NER0-1:
120°-~1-115°-~2-115 °-2~3-115°-~2-115 °-¢1-120°-~ r
where pulses 180 ° out of phase have an overbar, and delays ~k are given
by
~1 = 0. 1391(~0exc12n)
.c 2 = 0.6251( It~xc1210
2~ 3 = 0.4281(&0exc/2n)
~r = 0" 2221(A~exc/2~)
Here (A~0exc/2,) is the offset frequency (Hz) of the center of the
excited spectral region. This class of pulse sequence is capable of
providing solvent suppression almost free from undesirable phase
distortions.