The pulsed-field gradients (PFGs) have become a very important element in any modern NMR pulse sequence. See a list of gradient-based building blocks in NMR.

Easy implementation on AVANCE spectrometers equipped with gradient technology.

Gradients are usually applied on standard conditions. The most important parameters to consider is their duration and their strength.

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

... 50u UNBLKGRAD ... p16:gp1 d16 ... 4u BLKGRAD

in which:

• p16 is the duration of the gradient (in microseconds)
• d16 is the recovery time (in seconds) needed after the gradient
• gp1 is the gradient strength defined in the gpz1 command. Otherwhise, gpnam1 defines the shape of the gradient.
• Before apply a gradient into a sequence, it is necessary to unblank the gradient in order don't perturb the lock signal, with the UNBLKGRAD command. On the other hand, at the end of the pulse sequence and before the acquisition period, it is necessary to blanking again by the BLKGRAD command.