In special situations it can be advisable to perform ¹H acquisition with selective X-decoupling in inverse ¹H-X detected experiments of natural abundance and isotopically enriched compounds. Thus during ¹H acquisition, selective decoupling of X (¹³C, ¹⁵N ...) is performed from an independent channel using a low-power continuous-wave irradiation.

Easy implementation on AVANCE spectrometers.

 For more experimental details see Tutorials: Calibration pulses.

The standard way to implement a selective heteronuclear decoupling is:

... 2 d1 do ... d12 pl14:f2 go=2 ph31  cw:f2 ... d12 do:f2 ...

in which:

• go starts data acquisition during an acq period using the acquisition parameters previously defined in eda.
• Broadband heterodecoupling is performed at low power (pl14) from the f2 channel using the cw:f2 command.
• The number after go (=2) defines the loop to be executed. The number of times this loop is repeated is governed by the number of scans (ns).
• ph31 is the receiver phase specified at the end of pulse program and must be cycled in accordance to all pulses involved in the pulse sequence.
• Selective heterodecoupling is stopped using the do command.