Two different multidimensional pulsed field gradient sequences are compared
which have the purpose of correlating spin displacements in different time
intervals with each other. The simplest possible sequence, three-pulse SER
PENT, measures displacements in two interleaved time intervals, while in VE
XSY, consisting of two independent pairs of gradient pulses separated by a
mixing time, displacements during the two encoding intervals are compared t
o each other. The formalism for both sequences is discussed in q space and
in displacement space and common features as well as differences between th
e two types of experiments are highlighted, employing the particular case o
f the concurrent VEXSY scheme which allows treatment according to both form
alisms. (C) 2001 Academic Press.