If a 180º proton pulse is applied in the middle of a delay, ¹H chemical shift is refocused but ¹H-¹H coupling constants are allowed to evolve.

 

Easy implementation on AVANCE spectrometers.

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

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

... d4 p2 ph1 d4 ...

in which:

• d4 is the variable evolution delay optimized to 1/(4*J) (in seconds).
• p2 is the 180º ¹H pulse (in microseconds) applied at high power level pl1 from the f1 channel.
• ph1 is the phase specified at the end of pulse program.

It should be possible to use equal gradients bracketing the 180 pulse.