Abstract
Two main research areas are covered by this thesis which describe pulse
sequence development for magic-angle spinning (MAS) solid-state nuclear
magnetic resonance (NMR): Resolution enhancement by dipolar-driven spinstate-
selective excitation and refocused continuous-wave heteronuclear decoupling.
Analytically and Optimal Control-based dipolar-driven spin-state selective
excitation schemes are presented as means of avoiding line broadening in
MAS solid-state NMR spectra of carbonyl resonances due to the scalar coupling
to the -carbon in 13C-labelled samples. The analytically developed
pulse sequences combine dipolar-recoupling elements of dierent recoupling
conditions in order to obtain spin-state selection. Correspondence between
analytically obtained results, simulations, and experimental results are presented
and further improvements for general applicability are proposed. The
Optimal Control-based sequences show a remarkable eciency reaching the
theoretical transfer bounds in simulations and close to this experimentally.
The sequences, however, depends on the spin-system geometry and future
guidelines for achievement of general applicable sequences are outlined.
Refocused continuous-wave (rCW) decoupling is presented as an e-
cient and robust means of decoupling abundant spins in order to obtain
high-resolution MAS solid-state NMR spectra of low-
(gyromagnetic ratio)
nuclei. The scheme is developed through a thorough average Hamiltonian
analysis of CW decoupling and thereof derived incorporation of averaging
refocusing-pulses. The rCW sequences show state-of-the-art decoupling
performance combined with stability towards rf-amplitude varia-
tions, -frequency osets, and -inhomogeneity as well as robustness on a very
wide range of chemical shift anisotropies. The sequences are introduced as
means of proton decoupling, however, the robustness towards chemical shift
anisotropy makes rCW suitable for uorine-19 decoupling, for which stateof-
the-art decoupling performance is presented. Furthermore, very eective
decoupling in diluted spin systems is demonstrated. Together with ease
of application and optimisation, rCW is ideal for low-sensitivity samples,
where thorough optimisation of decoupling schemes are rendered impossible.
These characteristics makes the rCW sequences broadly applicable.
sequence development for magic-angle spinning (MAS) solid-state nuclear
magnetic resonance (NMR): Resolution enhancement by dipolar-driven spinstate-
selective excitation and refocused continuous-wave heteronuclear decoupling.
Analytically and Optimal Control-based dipolar-driven spin-state selective
excitation schemes are presented as means of avoiding line broadening in
MAS solid-state NMR spectra of carbonyl resonances due to the scalar coupling
to the -carbon in 13C-labelled samples. The analytically developed
pulse sequences combine dipolar-recoupling elements of dierent recoupling
conditions in order to obtain spin-state selection. Correspondence between
analytically obtained results, simulations, and experimental results are presented
and further improvements for general applicability are proposed. The
Optimal Control-based sequences show a remarkable eciency reaching the
theoretical transfer bounds in simulations and close to this experimentally.
The sequences, however, depends on the spin-system geometry and future
guidelines for achievement of general applicable sequences are outlined.
Refocused continuous-wave (rCW) decoupling is presented as an e-
cient and robust means of decoupling abundant spins in order to obtain
high-resolution MAS solid-state NMR spectra of low-
(gyromagnetic ratio)
nuclei. The scheme is developed through a thorough average Hamiltonian
analysis of CW decoupling and thereof derived incorporation of averaging
refocusing-pulses. The rCW sequences show state-of-the-art decoupling
performance combined with stability towards rf-amplitude varia-
tions, -frequency osets, and -inhomogeneity as well as robustness on a very
wide range of chemical shift anisotropies. The sequences are introduced as
means of proton decoupling, however, the robustness towards chemical shift
anisotropy makes rCW suitable for uorine-19 decoupling, for which stateof-
the-art decoupling performance is presented. Furthermore, very eective
decoupling in diluted spin systems is demonstrated. Together with ease
of application and optimisation, rCW is ideal for low-sensitivity samples,
where thorough optimisation of decoupling schemes are rendered impossible.
These characteristics makes the rCW sequences broadly applicable.
| Originalsprog | Engelsk |
|---|---|
| Status | Udgivet - okt. 2012 |
| Udgivet eksternt | Ja |