If a 180º proton pulse is applied in the middle of a delay, proton chemical shift is refocused but proton-proton coupling constants allow to evolve. This is the basis of the homonuclear 2D J-resolved Spectroscopy.

Easy implementation on AVANCE spectrometers.

Only the evolution delay must be set in accordance to the required application.

The standard way to implement a variable homonuclear spin-echo period in a pulse program is:

... d0 p2 ph1 d0 ...

in which:

• d0 is the variable evolution delay (in seconds).
• p2 is the 180º ¹H pulse (in microseconds) applied at a power level pl1 from the f1 channel.
• ph1 is the phase specified at the end of pulse program.