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arXiv · 2109.05453

Concurrent J-Evolving Refocusing Pulses

Sebastian Ehni·Martin R. M. Koos·Tony Reinsperger·Jens D. Haller·David L. Goodwin·Burkhard Luy
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Abstract

Conventional refocusing pulses are optimised for a single spin without considering any type of coupling. However, despite the fact that most couplings will result in undesired distortions, refocusing in delay-pulse-delay-type sequences with desired heteronuclear coherence transfer might be enhanced considerably by including coupling evolution into pulse design. We provide a proof of principle study for a Hydrogen-Carbon refocusing pulse sandwich with inherent J-evolution following the previously reported ICEBERG-principle with improved performance in terms of refocusing performance and/or overall effective coherence transfer time. Pulses are optimised using optimal control theory with a newly derived quality factor and z-controls as an efficient tool to speed up calculations. Pulses are characterised in detail and compared to conventional concurrent refocusing pulses, clearly showing an improvement for the J-evolving pulse sandwich. As a side-product, also efficient J-compensated refocusing pulse sandwiches -- termed BUBU pulses following the nomenclature of previous J-compensated BUBI and BEBE(tr) pulse sandwiches -- have been optimised.

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Sebastian Ehni, Martin R. M. Koos, Tony Reinsperger, Jens D. Haller, David L. Goodwin, Burkhard Luy. 2021-09-12. Concurrent J-Evolving Refocusing Pulses. https://doi.org/10.1016/j.jmr.2022.107152

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