# liquid.m

Liquid-phase interface to pulse sequences. Generates a Liouvillian superoperator and passes it on to the pulse sequence function, which should be supplied as a handle. This interface handles RDC mode -- if the 'rdc' need is specified, it would use the order matrix supplied by the user to compute the residual anisotropies of all interactions.

## Syntax

    fid=liquid(spin_system,pulse_sequence,parameters,assumptions)


## Arguments

 pulse_sequence     - pulse sequence function handle. See the
experiments directory for the list of
pulse sequences that ship with Spinach.

parameters.spins   - a cell array giving the
spins that the pulse sequence works on, in
the order of channels, e.g. {'1H','13C'}

parameters.offset  - a cell array giving
transmitter offsets on each of the spins
listed in parameters.spins array.

parameters.needs   - a cell array of strings specifying additional
information required by the sequence:

'zeeman_op' - Zeeman part of the Hamiltonian
in the laboratory frame, to be placed into
parameters.hseeman and sent to pulse sequence

'rdc' - triggers the processing of residual
anisotropic couplings due to partial order

parameters.rframes - rotating frame specification, e.g.
{{'13C',2},{'14N,3}} requests second
order rotating frame transformation
with respect to carbon-13 and third
order rotating frame transformation
with respect to nitrogen-14. When
this option is used, the assumptions
on the respective spins should be
laboratory frame.

parameters.*        - additional subfields may be required by your
pulse sequence - check its documentation page

assumptions       -  context-specific assumptions ('nmr', 'epr',
'labframe', etc.) - see the pulse sequence
header for information on this setting.


## Outputs

This function returns whatever it is that the pulse sequence returns.

## Examples

There are over 100 examples using this context in the example set. The following cases are representative:

dnp_liquids/dnp_liquid_1.m - Overhauser DNP in an electron-nucleus spin system

esr_liquids/relaxation_nitroxide.m - g-hyperfone cross-correlated relaxation in EPR of nitroxide

kinetics/glucose_exsy.m - NOESY and EXSY spectrum of fluorinated glucose in blood

liquid_crystals/rdc_four_spin.m - residual dipolar coupling HSQC in a four-spin system

nmr_proteins/noesy_ubiquitin_theo.m - NOESY spectrum of ubiquitin

nmr_zerofield/zero_field_methanol.m - zero-field NMR spectrum of methanol

spin_chemistry/singlet_yield_1.m - magnetic field dependence of singlet yield in a radical reaction

## Notes

Arbitrary order rotating frame transformation is supported, including infinite order. See rotframe.m for further information.