Hi,
In version 2_7_6049, I could simulate the effects of SRSK on a spin-1/2 spectrum when the relaxation rate of the quadrupolar nucleus was rather slow.
For example in the 1H - 11B case, if used inter.relaxation={'t1t2', 'SRSK'} I could set r1/r2 for the quadrupoar nucleus to be of the order of the coupling constant and generate a 1D 1H spectrum with a 1:1:1:1 quartet with broadened lines. If the r1/r2 are set much larger than J, this would reduce to a singlet, which gets sharper for faster quadrupolar relaxation, if r1/r2 are set very small I get sharp multiplet components in the proton spectrum.
I think I made a mistake in the calculation here though: I've not specified
inter.srsk_sources=2;
(the list of spins being 1H, 11B).
If I specify this, then the linewidth simply increases with decreasing set r1/r2 of the quadrupolar nucleus. For a given (large) quadrupolar relaxation rate, the width of the proton signal is larger than if inter.srsk_sources=2; is missing.
So I'm slightly confused as to what's going on! I see that in 2.12.1 there is a check against the relaxation rates being too slow; it aborts if this is the case, and also fails if inter.srsk_sources is not specified, which is how I realised there was something wrong with my original calculation.
Is there any convenient way to (correctly) calculate the scalar relaxation in the case of slow quadrupolar relaxation? (in spinach or otherwise!) What, if anything, is the meaning of the calculations I originally did (where the linewidth depends on the quadrupolar relaxation rate and I can see the multiplet in the limit of slow quadrupolar relaxation)?
Thanks for any thoughts!
Pete