Simulation of the radiation damping artifacts in 2D COSY NMR experiments using the Q-switch technique

The mutual effects of radiation damping and relaxation in two-dimensional correlation (COSY) experiments are discussed. Multiple-quantum (MQ)-like artifacts in 2D COSY experiments using Q-switch are simulated under three different conditions: (i) no damping during t1 but radiation damping during t2; (ii) relaxation damping during t1 and radiation damping during t2; (iii) relaxation damping and weak radiation damping during both t1 and t2. It is shown that when radiation damping effects during t1 are reduced by switching Q to low but are strong during t2 by switching Q to high, MQ-like artifacts can be expected. However, relaxation effects during t1 can strongly influence the lineshape of the artifacts.