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

Create a new dataset with edc and read the standard parameter set to perform selective ¹H excitation with rpar SELZG1H all (the pulse program selzg can be displayed with the edcpul command). 

The most important parameters to modify are the shape, the duration and the corresponding power level of the selective pulse (p11). For selective excitation, a 80 ms gaussian shape truncated to 5% is a good starting point (p11=80ms and spnam1=gauss1024). The shape must be created from the xShape tool and the power level (sp1) must be calibrated.

o1 is set on-resonance of a well-isolated selected resonance.

For instance, set sp1 to 70dB and start data acquisition with rga and zg.  Transform the recorded data with ef (lb=1) and correct the phase for this signal. Check that selective excitation is achieved in a single scan (ns=1 and ds=0). A plot region including this resonance (using the DefPlot button) must be defined.

Execute the AU paropt program in order to calibrate the selective 90º pulse. Answer the questions as follows:
 
             Enter parameter to modify:             sp1
             Enter initial parameter value:          60
             Enter parameter increment:               1
             Enter # of experiments:                    21
 
In this case, paropt automatically acquires 21 spectra while incrementing the parameter sp1 from 60dB to 80dB.

Each spectra is automatically processed with the defined lb value (usually lb=1) and for each value of sp1, only the spectral region defined above is plotted. All spectra appear side-by-side in the corresponding procno 999. The maximum value is the selective 90º proton pulse. In some cases, it can be advisable to use the corresponding self-refocusing 270 degree pulse.

From this calibration, we can use other selective pulse lengths and power levels as a function of the required selectivity. Each 6 dB, the pulse duration is doubled and each 20 dB, the pulse duration is multiplied by 10. On the other hand, the duration of the corresponding selective 180º pulse is the double of the calculated selective 90º pulse at the same power level. The following table can be used as a reference:
 
 

	10 ms	20 ms	40 ms	80 ms	100 ms
selective 90º	61	67	73	79	81
selective 180º	55	61	67	73	75
selective 270º	52	58	64	70	72

 

Once the calibration has been succesfully carried out, the parameter set can be stored with the wpar command in order to be used in the future (for instance, wpar selzg all).

When applying selective 90 or 270 degree pulses in other sequences, there is need for phase difference calculation between power levels sp1 and pl1. This phase correction must be applied on the selective pulses.