# M61

From relax wiki

The Meiboom 1961 2-site on-resonance fast exchange relaxation dispersion model for R1rho-type data. This model is labelled as **M61** in relax.

## Equation

[math] \mathrm{R}_{1\rho}= \mathrm{R}_{1\rho}{´} + \frac{\Phi_\textrm{ex} \textrm{k}_\textrm{ex}}{\textrm{k}_\textrm{ex}^2 + \omega_\textrm{e}^2} [/math]

## Parameters

The M61 model has the parameters {R_{1ρ}', ..., *Φ _{ex}*, k

_{ex}}.

## Reference

The reference for the M61 model is:

- Meiboom, S. (1961). Nuclear magnetic resonance study of proton transfer in water.
*J. Chem. Phys.*,**34**(2), 375-388. (10.1063/1.1700960).

## Related models

The DPL94 model is an extension of the M61 model for off-resonance data.

## Links

The implementation of the M61 model in relax can be seen in the: