Measurement of small spin–spin splittings in the presence of chemical exchange: case of deuteriated water

Abstract

A new implementation of a described data processing for measuring small scalar coupling constant J is proposed. It is applied particularly to situations where the coupling constant is around the linewidth at half-height, and in the presence of chemical exchange. This modified data processing uses only a simple “one-pulse” experiment instead of a series of spin echoes experiments required by the previous processing. The FID recorded in the one pulse experiment is used by a reconstitution program to generate a set of signals, which are analyzed in the time domain to obtain a spectrum where the scalar coupling constant is apparently multiplied by n+1, where n is positive. The new processing is tested with simulated spectra. The coupling constant between proton and deuterium is measured in the proton spectrum of a solution of 80% of D 2O and 20% of H 2O. It was found to be J=1.54±0.01 Hz .