hsqcetgpsi.m

Sensitivity-improved echo/antiecho gradient-selected HSQC pulse sequence, based on the Bruker hsqcetgpsi 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
          https://doi.org/10.1016/0022-2364(91)90036-S
          https://doi.org/10.1021/ja00052a088
          https://doi.org/10.1007/BF00175254

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. The front end is that of hsqcetgp.m: a 90-degree F2 pulse, an INEPT block of total duration 1/(2J) split in half by simultaneous 180-degree pulses on both channels, an F2 trim pulse of the user-specified angle, and the transfer pulses, of which 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, and 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. The sensitivity improvement block that follows consists of a 90-degree pulse pair on F2 and F1 about X, a delay of parameters.si_time, simultaneous 180-degree pulses on both channels, a second delay of parameters.si_time, and a 90-degree pulse pair on F2 and F1 about Y. The back-transfer evolution of total duration 1/(2J) is then refocused by simultaneous 180-degree pulses, and is followed by a 90-degree and a 180-degree F2 pulse before the second gradient, which 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=hsqcetgpsi(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

    parameters.si_time            sensitivity improvement delay, s

    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

hsqcetgp.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