# r2csa2tauc.m

Estimates the rotational correlation time from the longitudinal CSA relaxation rate.

## Syntax

    tauc=r2csa2tauc(R1,del_sq,B0,isotope


## Description

This function solves the Redfield relaxation theory (rotationally modulated CSA induced transverse relaxation) expression back for the rotational correlation time. Make sure your CSA is in fractions, not ppm.

## Arguments

   R2      - transverse relaxation rate, Hz

del_sq  - second rank invariant of the CSA,
see blinv.m function

B0      - magnetic field, Tesla

isotope - isotope specification string, e.g. '1H'


## Outputs

    tauc    - rotational correlation time, seconds


## Notes

Most relaxation rates are not solely due to CSA, and so the result is an estimate. If you get the "no real solutions" error, you relaxation is certainly not CSA dominated.