hsqcetgp.m

Echo/antiecho gradient-selected HSQC pulse sequence, based on the Bruker hsqcetgp pulse program and the standard HSQC sequence from:

          https://doi.org/10.1016/0009-2614(80)80041-8
          https://doi.org/10.1002/cmr.a.10095

The gradient selection is represented analytically by coherence order selection statements.

The simulation runs in the spherical tensor Liouville space formalism, and starts from Lz on the F2 nucleus. A 90-degree F2 pulse is followed by an INEPT block of total duration 1/(2J) that is split in half by simultaneous 180-degree pulses on both channels, then by an F2 trim pulse of the user-specified angle, and then by the transfer pulses; the F1 90-degree pulse enters as the difference between the results of the +90 and the -90 degree rotations. The indirect dimension is evolved in two halves, with 180-degree refocusing pulses on the isotopes listed in parameters.decouple_f1 applied at the midpoint. The first gradient pair is replaced by two coherence.m calls that keep F2 coherence order zero together with F1 coherence order +1 in the echo branch and -1 in the antiecho branch. Both branches then receive an F1 inversion pulse, simultaneous 90-degree back-transfer pulses, and a second refocused evolution period of total duration 1/(2J); the second gradient is represented by selection of F1 coherence order zero and F2 coherence order +1 in both branches. Decoupling of the isotopes listed in parameters.decouple_f2 is applied by decouple.m, and L+ on the F2 nucleus is detected in the direct dimension.

Syntax

    fid=hsqcetgp(spin_system,parameters,H,R,K)

Parameters

    parameters.sweep              [F1 F2] sweep widths, Hz

    parameters.npoints            [F1 F2] numbers of points

    parameters.spins              {F1 F2} nuclei (e.g. '13C','1H')

    parameters.decouple_f2        nuclei to decouple in F2, e.g.
                                  {'15N','13C'}

    parameters.decouple_f1        nuclei that receive midpoint
                                  180-degree refocusing pulses in
                                  F1, e.g. {'1H','13C'}

    parameters.J                  working scalar coupling, Hz

    parameters.trim_angle         proton trim pulse angle, rad

    H  - Hamiltonian matrix, received from context function

    R  - relaxation superoperator, received from context function

    K  - kinetics superoperator, received from context function

Outputs

    fid.pos,fid.neg -  echo and antiecho components of the
                       signal.

Notes

Natural abundance simulations should make use of the isotope dilution functionality. See dilute.m function.

The function is only available for the sphten-liouv formalism, and parameters.decouple_f1 must not contain the F1 isotope itself.

See also

hsqcetgpsi.m, hsqc.m, ct_hsqc.m, clip_hsqc.m, hmqc.m, coherence.m, decouple.m, dilute.m, Built-in experiments

Version 2.13, authors: Ilya Kuprov