CR72

The Carver and Richards 1972 2-site relaxation dispersion model for SQ CPMG-type data for most time scales whereby the simplification $R_{2A}^0$ = $R_{2B}^0$ is assumed. This model is labelled as CR72 in relax.

Equation

Please see the summary of the model parameters here.

[math] R_{2,\textrm{eff}} = \frac{R_2^A+R_2^B+k_{\textrm{EX}}}{2} - \nu_{\textrm{cpmg}} \cosh^{-1} (D_+\cosh(\eta_+) - D_-\cos(\eta_-)) [/math]

Parameters

The CR72 model has the parameters {$R_2^0$, $...$, $p_A$, $\Delta\omega$, $k_{ex}$}.

Reference

The reference for the CR72 model is:

• Carver, J. and Richards, R. (1972). General 2-site solution for chemical exchange produced dependence of T2 upon Carr-Purcell pulse separation. J. Magn. Reson., 6(1), 89-105. (10.1016/0022-2364(72)90090-X).

Related models

The CR72 model is a parametric restriction of the CR72 full model.

Links

The implementation of the CR72 model in relax can be seen in the:

• relax manual,
• API documentation,
• relaxation dispersion page of the relax website.