Gating the Decoupler On/Off for Heternuclear Experiments

In many cases, it might be desireable to turn the 1H Decoupler off for some or all of the Pulse Sequence when observing heteronuclei such as 13C, 11B, 31P, 29Si, or 15N.

On Varian instruments, the decoupling can be gated On or Off during different times of the experiment using the parameter "dm" (lowercase).

• dm='nnn' turns off the decoupler entirely
• dm='nny' turn on the decoupler during the acquisition and off during the pre-acquisition delay.
  • Note: this is often referred to "inverse gated decoupling" to eliminate NOE enhancements while still decoupling 1H.
• dm='ynn' will turn on the decoupler during the relaxation delay (d1), but off during the acquisition of the FID.
  • Note: this is often referred to as "gated decoupling" to provide NOE enhancement during d1, but 1H is not decoupled during acquisition.

After setting up your normal acquisition parameters (i.e. [Setup] [Nucleus,Solvent] ), just type dm='nnn', or dm='nny', or dm='ynn' prior to starting the acquisition using the ga or go command.