The ROESY block consists of an spin-lock (SL) field applied along an specific x,y axis during which the nuclei relax. This SL can be a low-power continuous-wave period or a  train of hard 180º pulses alternated in phase (T-ROESY).The advantage over the NOESY block is that Overhauser enhancement is always positive, never approaching zero.

The process follows as:

• Before the ROESY block, in-phase transverse magnetization of the target spin (I_1x) is required.
• The magnetization is transferred to other spins via dipolar coupling or exchange processes. The final result is in-phase magnetization of the relayed spins (I_2x+ I_3x + I_4x ...).

Other approaches includes an off-resonance spin-lock or the T-ROESY approach.

Easy implementation on AVANCE spectrometers.

 See  2D ROESY and related experiments.

The standard way to implement a ROESY block is:

... d12 pl11 p15 ph2 ...

in which:

• p15 is the mixing ROESY pulse (in usec) applied at low power level pl11 from the f1 channel.
• d12 is the minimum delay (20 msec) to set pl11.
• The phase may be specified at the end of pulse program.

 See  2D ROESY and related experiments.