Single-Spin Vector Analysis of Strongly Coupled Nuclei in TOCSY NMR Experiments

TY - JOUR

T1 - Single-Spin Vector Analysis of Strongly Coupled Nuclei in TOCSY NMR Experiments

AU - Nielsen, Anders Bodholt

AU - Hansen, Michael Ryan

AU - Andersen, Jørgen Ellegaard

AU - Vosegaard, Thomas

PY - 2019

Y1 - 2019

N2 - This paper presents a new way to represent the effect of complex radio-frequency (rf) pulse sequences on J-coupled nuclear spin systems. The model uses a vector representation of the single-spin interactions (chemical-shift and rf interactions) and provides a simple route to gain analytical insight into multipulse NMR experiments. The single-spin Hamiltonian is expressed in an interaction representation as Fourier components. These Fourier components are combined for the two spins to establish the averaged coupling term of the Hamiltonian. This effective Hamiltonian is fast to calculate as only single-spin rotations are used and followed by simple summation of numbers for reconstruction of given coupling interactions. The present method is used to gain analytical insight into the performance of the J-coupling transfer sequence DIPSI-2 through two figures of merit (FOM) providing useful information for optimization of such pulse sequences. The first FOM (ΞAB) reports the efficiency of the desired total correlation spectroscopy transfer and should be as large as possible, while the second (ΞHet) reports the potential leakage of coherence to a heteronuclear spin and should be as small as possible.

AB - This paper presents a new way to represent the effect of complex radio-frequency (rf) pulse sequences on J-coupled nuclear spin systems. The model uses a vector representation of the single-spin interactions (chemical-shift and rf interactions) and provides a simple route to gain analytical insight into multipulse NMR experiments. The single-spin Hamiltonian is expressed in an interaction representation as Fourier components. These Fourier components are combined for the two spins to establish the averaged coupling term of the Hamiltonian. This effective Hamiltonian is fast to calculate as only single-spin rotations are used and followed by simple summation of numbers for reconstruction of given coupling interactions. The present method is used to gain analytical insight into the performance of the J-coupling transfer sequence DIPSI-2 through two figures of merit (FOM) providing useful information for optimization of such pulse sequences. The first FOM (ΞAB) reports the efficiency of the desired total correlation spectroscopy transfer and should be as large as possible, while the second (ΞHet) reports the potential leakage of coherence to a heteronuclear spin and should be as small as possible.

U2 - 10.1063/1.5123046

DO - 10.1063/1.5123046

M3 - Journal article

C2 - 31594312

SN - 0021-9606

VL - 151

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

IS - 13

M1 - 134117

ER -