Genetic algorithms and solid state NMR pulse sequences

TL;DR

This paper explores using genetic algorithms to optimize solid state NMR pulse sequences, specifically improving the C7 dipolar recoupling sequence for better efficiency and robustness in complex spin systems.

Contribution

It demonstrates the application of genetic algorithms to optimize NMR pulse sequences, resulting in more efficient and robust sequences with minimal prior system knowledge.

Findings

Optimized pulse sequence is robust over a wide parameter range.

Requires minimal a priori knowledge for experimental implementation.

Breaks the synchronicity between RF pulses and sample spinning.

Abstract

The use of genetic algorithms for the optimisation of magic angle spinning NMR pulse sequences is discussed. The discussion uses as an example the optimisation of the C7 dipolar recoupling pulse sequence, aiming to achieve improved efficiency for spin systems characterised by large chemical shielding anisotropies and/or small dipolar coupling interactions. The optimised pulse sequence is found to be robust over a wide range of parameters, requires only minimal a priori knowledge of the spin system for experimental implementations with buildup rates being solely determined by the magnitude of the dipolar coupling interaction, but is found to be less broadbanded than the original C7 pulse sequence. The optimised pulse sequence breaks the synchronicity between r.f. pulses and sample spinning.