\eta_- = \frac{\sqrt[3]{4}}{\nu_{\textrm{cpmg}}}\sqrt{-\Psi + \sqrt{\Psi^2 + \zeta^2}}
</math>
<math>k_{\textrm{EX}}</math> is the chemical exchange rate constant, pA and pB are the populations of states A and B, and <math>\Delta \omega</math> is the chemical shift difference between the two states in ppm.
== Parameters ==