Selective homonuclear 1D experiments usually start from the selective ¹H excitation of a given resonance followed by a mixing process. An important point to consider in such experiments is the chosen selective excitation scheme. The most simple approach is a 90º or 270º shaped pulse.

or a selective spin-echo scheme:

When PFGs are available, the SPFGE and DPFGE schemes are highly recommended. There are two different types of homonuclear experiments as a function of the mixing process:

• Antiphase ¹H magnetization is required before the mixing process (COSY-type experiments). In this case, we can use a self-refocusing selective scheme followed by a fixed period optimized to 1/(2*J_HH). If a non-refocusing pulse is used, J-evolution during the long selective pulse must be taking in account.
• In-phase ¹H magnetization is required before the mixing process (NOESY-, ROESY- and TOCSY-type experiments). In this case, there is no need for the evolution period and therefore, the mixing process can start immediately after the self-refocusing selective scheme.

Easy implementation on AVANCE spectrometers equipped with shaped pulses capability.

For further details about implementation of selective excitation schemes and selective 1D experiments in AVANCE spectrometers see:

• Tutorials on Selective Excitation schemes
• Tutorials on Selective 1D Experiments
• Tutorials on Shaped pulses

The most standard way to implement an initial selective 90º or 270º ¹H pulse in a pulse program is:

...  4u pl0:f1 p11:sp1:f1 ph1:r ...

in which

• p11 is the duration of the shaped pulse
• sp1 is the power level of the selective pulse. pl0 is set to 120dB
• spnam1 is the shape of the selective pulse
• phcor1 is the phase difference between hard and soft pulses.

See theoretical descriptions of related experiments in the following lists: Selective excitation schemes
Selective homo- and heteronuclear 1D experiments
Selective gradient-based 1D experiments