Insert the sample (ij).

Choose the solvent deuterium signal with the lock command

Tune and match the probehead (wobb or atma if required).

Optimize the shim procedure (read an optimized shim file with the rsh command or performs a gradshim if required).

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

Record a SPFGE experiment on the selected 1H resonance to be selectively excited. Check for the proper values of p12 and sp2.

Create a new dataset (new) and read the standard BRUKER parameter set (rpar) to record a Selective gradient-enhanced 1D COSY experiment with rpar SELCOGP all and change the pulse program to selrelgp can be visualized in the PulsProg section or with the edcpul command).

Update the corresponding pulses and power levels in the acquisition parameters according to the selected solvent/probehead parameters by executing the getprosol command (pulses and power levels must be correctly set by the edprosol command). If required, any acquisition parameter can be modified manually or in the AcquPars section.

The most relevant parameters for an optimum selective excitation using SPFGE are:

p12 is the duration of the selective 180 pulse

sp2 is the required power level for a given shape defined in spnam2

spoffs2 is the offset (in Hz) to be selectively excited with respect to the center of the spectrum (o1)

d4 is the J-coupling evolution period (must be optimized to 1/2J(HH)). You can start with a value of 40 ms.

d5 is the second J-coupling evolution period (must be also optimized to 1/2J(HH)). You can start with a value of 40 ms.

A minimum two-scan cycle is needed (ns=2 and ds=2).

Start acquisition by rga and zg (the expected experimental time is displayed with the expt command).

Transform the acquired data with ft and corrects the phase (relay and COSY peaks must present an anti-phase pattern).

Use the TOPSPIN plot editor (xwinplot)

It can be advisable to store all acquisition and processing parameters (with the command wpar) to be used later.

The best option is to use the shorter selective 180º pulse that achieve clean excitation of the selected resonance without disturb other resonances. In some cases, the use of long selective pulses can undergo sensitivity losses due to relaxation effects.

The selective ge-1D RELAY experiment can also be recorded using a DPFGE scheme as a starting building block (See the DPFGE experiment for more details).

Multiple-step RELAY experiments can be designed by adding successive RELAY blocks before acquisition. Selective 1D TOCSY experiments using different mixing times is an alternative approach to elucidate spin subsystems.