NMR Valtice, 2016, 31th Central European NMR Meeting
Sprache des Tagungstitel:
The vast majority of solid-state NMR experiments? ?in existence today? ?is based on development and analyses by average Hamiltonian theory? (?AHT?) [?1?]?.? ?After formulation of AHT in the late? ?60th the limitations of this approach quickly became apparent too.? ?Especially presence of multiple anisotropic spin-interactions together with simultaneous spin-modulation by radio-frequency pulses and sample rotation at the magic-angle,? ?present multi-parameter scenarios that are mostly intractable by means of analytical calculations by AHT.? ?These limitations brought computer based search and? ?optimisation techniques,? ?like optimal control theory? (?OCT?) [?2?]?,? ?to the scene.?
Optimisation,? ?especially when conducted by computers requires measures? (?figures of merit?) ?by which to quantitatively assess the quality of a solid-state NMR pulse sequences.? ?Historically spectroscopists use terms like:? ?efficient,? ?broadbanded,? ?selective,? ?sensitive,? ?robust,? ?high-resolution,? ?low-power,? ?etc.? ?for this purpose.? ?While it is relatively straight forward to quantitatively asses NMR experiment with respect to a single one of these qualities,? ?optimisation with respect to two or more simultaneously,? ?poses a considerable challenge due to the different characters of these qualities.
Here we demonstrate how such multi-objective optimisation problems can be tackled in an intuitive fashion by using the concept of Pareto optimality in connection with a genetic algorithm optimisation approach.?