SpinDynamics.org User Support Forum

Hi all,

If possible, I'd be happy to get help with the following issues I encountered when wishing to perform an ESEEM pulse sequence in the lab frame for a spin 1 system (focusing on a specific transition, with ZFS) using the eseem pulse sequence function:

1) Is it possible to use 'trajectory' and 'refocus' (with rho_stack) if I have to track the phase of the in-between soft pi pulse in the lab frame (which I should track right?, when using "shaped_pulse_af" and not "step"?)
2) Generally: say I am interested in the projection of the |i><i| state on rho_final (Tr[|i><i|*rho_final]) and not the S_j expectancy value, how can I calculate it efficiently without reshaping the output vector? and how to normalize it correctly (using the 'sphten-liouv' basis)?
3) For some reason, which is not clear to me, when I use "shaped_pulse_af" to give a pi pulse, with an amplitude of 10e6 rather than 100e6, I obtain only a partial flip of the state, although using the appropriate pulse duration (1/sqrt(2)*pi/amplitude). I expected it to be the same in both cases.
4) What is the screen state used for?

Thanks,
Ariel

Hint: people will not do your project for you.

1. Yes; you do need to track the clock because phases in magnetic resonance are relative to the reference clock.

2. There is no way; Spinach uses a spherical tensor basis set. Express your projector in that basis set and then take the inner product.

3. Check for 2*pi factors between Hz and rad/s and also try increasing the rank.

4. Very rarely, we are only interested in the amplitude of one specific state at the end of the evolution. In that case, it is possible to ignore all dynamics that does not lead to or influence that state. This accelerates the calculation. If in doubt, do not specify a screen state.

Thank you for the answers!