th  - 1987 - 51st ENC Conference

MF55
DYNAMIC PARAMETERS FROM NONSELECTIVELY GENERATED ID EXCHANGE SPECTRA
Charles G. Wade, Mark O'Neil-Johnson, and Eric R. Johnston
IBM Instruments, Inc.
40 Airport Parkway
San Jose, California 95110
We propose an experimentally and computationally simple method
for the direct measurement of the elements of the relaxation matrix
R which characterize dynamics in spin systems. The usual 2D exchange
pulse sequence (90 ° ) - t I - (90 ° ) - t m - (90o ) - t2(obs) is used,
with appropriate phase cycling for the cancellation of single quantum
and higher-order coherence during t m. For a system of N spins we
record spectra with and without mixing for N arbitrarily chosen values
of t I. This affords N 2 measureable intensities from which the N 2
elements of e -~tm can be generated and from which R itself can then
be calculated with a back-transformation method.
The utility of the method lies in the ease and speed with which
the experimental data are generated. Only nonselective transmitter
pulses are required so the method is easier to implement than other
schemes which employ DANTE or decoupler inversion pulses to perturb
the spin system prior to mixing. Time-consuming 2D data acquisition
and processing are similarly avoided. The method will be illustrated
with applications to multisite and scalar-coupled spin systems.