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== Calculations in relax ==
=== spin lock offset ===
In the literature, the values are often stated as "offset", "carrier offset", "offset of the spin-lock pulse" with values given in Hz, and can have values from 0-500 to 10-20.000 Hz.<br>
These values reflects offset frequencies to the carrier frequency, and in relax is noted as '''"Spin-lock offset, the frequency of of the rf field"''' : $\mathbf{\omega_{rf}}$.
offsets[ei][si][mi][oi] = frequency_to_rad_per_s(frq=cdp.spin_lock_offset[id], B0=frq, isotope=spin.isotope)
</source>
The offset is in the literature noted as $\Omega_S$, where $\Omega_S$ is the (Ex. $^{15}$N) resonance offset from the spin-lock carrier.
Note that $\Omega_S$ is dependent of the [[wikipedia:Chemical_shift | chemical shifts]] $\delta$ in ppm for the nuclei of interest, and is first calculated later.
=== spin lock field ===