Record a conventional ¹H spectrum. Note the o1 of the selected resonance.

Perform a selective excitation on this desired resonance. Note the required values of power level (sp1), shape (spnam1) and duration (p11) of the selective pulse.

The determination of the phase difference between hard and soft pulses is made from the standard ¹H parameter set defined in the conventional ¹H spectrum.

The values of o1, sp1, spnam1, and p11 are set as described in the preliminary set-up procedures.

1. A conventional ¹H spectrum using a read 90º pulse is recorded under routine conditions with rga and zg (ns=1 and ds=0). The data is transformed with ef (lb=1) and phase corrected as usual. If this process is repeated and the data is now processed with efp a phase corrected conventional ¹H spectrum is directly obtained.
2. Then, the pulse program is changed to perform selective exciation by typing pulprog selzg. The acquisition is started with zg using the same conditions as described above and the data is processed with efp. In this way, a ¹H spectrum only showing the selected resonance is displayed. This signal is manually phase corrected in the phase menu and the value of PH0 is noted (for instance, 70.5). Return to the main menu without store the correction and insert this additional phase correction in the eda menu by typing phcor1 70.5. If both data acquisition and processing are repeated, a properly phase corrected selective excitation is achieved.

This additional phase correction might to be applied to the shaped pulse only, not to the hard pulses, in all experiments involving selective excitation.