S. Habot et al., TIME SYMMETRY - AN APPLICATION TO SHAPED PULSE EXCITATION OF SPIN-1 SYSTEMS, Solid state nuclear magnetic resonance, 10(3), 1998, pp. 137-150
The role of time symmetry in the design of amplitude-modulated (shaped
) pulses for spin-1 excitation is examined. The quaternion calculus is
used to calculate the quaternion elements (Euler-Rodrigues parameters
) of each shaped pulse. In this manner, it is shown how the simplicity
and compactness of the Euler-Rodrigues parametrization can be used to
significantly expedite a computer search for optimal time-symmetric s
haped pulses. Theoretical and experimental tests of a new class of sym
metric quadrupole-shaped (SQUASH) pulses identified by this procedure
show a significant improvement in both excitation bandwidth and effici
ency in comparison to the time-asymmetric QUASH shaped pulse previousl
y identified. (C) 1998 Published by Elsevier Science Ltd.