Figure 5.

Intensity loss during R-CODEX experiments due to exchange during dephasing is illustrated with simulations that assume different dipolar couplings and motional rate constants. In (a) simulations assumed a two-site jump of a single ¹³C-¹H dipolar pair (with a coupling of 23.3 kHz), a reorientation angle of 120° and equal site populations. The solid lines are the single exponential fits to the discrete simulation results; rate constants so derived were perfectly consistent with the exchange rates assumed in the simulations. In (b) the parameters were the same as those used in (a) except that the dipolar coupling was reduced to 4.6 kHz. Note that the amplitude of magnetization is reduced, particularly for the faster motions, but the simulated decay constants are again perfectly consistent with the exchange rates assumed in the simulations.