  Long pulse durations necessary in selective inversion recovery (SIR)
experiments along with radiation damping (RD) introduce difficulties in
quantitative nuclear magnetic resonance measurements, such as those that allow
for the determination of a sample's characteristics, including the rates that
govern magnetization transfer. Because of these influences, the assumption of
perfect inversion is invalid. In this work, we present data that demonstrates
that long pulse durations as well as RD cause difficulties in SIR experiments
performed on simple one-spin systems, indicating that they will be problematic
for multiple-spin systems as well. These results emphasize the importance of
understanding the evolution of magnetization for all time points throughout an
experiment used in quantitative NMR measurements. Furthermore, experimental
parameters must be chosen carefully and understood completely.
