Abstract: The selective excitation NMR technique with Gaussian soft pulse has been used to record one-dimensional antiphase magnetization spectrum. The antiphase spectrum can be employed further to accurately measure J coupling constant by combining J-Doubling method. This measurement of J coupling constant is suitable particularly for overlapping multiplets and those with large spectra llinewidth and small coupling splitting.

Key words: Gaussian soft pulse, Selective excitation, Measurement of J coupling, J-Doubling