The RELAY block is an extension of the COSY block in which polarization of the relayed spin is transferred to a third spin by applying another 90º mixing pulse. Multiple RELAY steps can be consecutively added to achieve step-by-step polarization transfer into a coupling spin network. However, improved results can be obtained using a TOCSY block.

Easy implementation on AVANCE spectrometers.

 See  2D RELAY and related experiments.

The standard way to implement a two-step RELAY block is achieved by concatening a second RELAY block:

... p1 ph1 d0 p1 ph2 d2 p2 ph3 d2 p1 ph4 d3 p2 ph5 d3 p1 ph6 ...

in which:

• p1 and p2 are the 90 and 180 pulses applied at high power level pl1 from the f1 channel.
• d2 and d3 are the first and second-step evolution delays optimized to an average 1/(3.2*J) value
• All phases may be specified at the end of pulse program.

 See Tutorial: 2D ¹H RELAY experiment