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Feedback control optimisation of ESR experiments

Feedback control optimisation of ESR experiments
Feedback control optimisation of ESR experiments
Numerically optimised microwave pulses are used to increase excitation efficiency and modulation depth in electron spin resonance experiments performed on a spectrometer equipped with an arbitrary waveform generator. The optimisation procedure is sample-specific and reminiscent of the magnet shimming process used in the early days of nuclear magnetic resonance – an objective function (for example, echo integral in a spin echo experiment) is defined and optimised numerically as a function of the pulse waveform vector using noise-resilient gradient-free methods. We found that the resulting shaped microwave pulses achieve higher excitation bandwidth and better echo modulation depth than the pulse shapes used as the initial guess. Although the method is theoretically less sophisticated than simulation based quantum optimal control techniques, it has the advantage of being free of the linear response approximation; rapid electron spin relaxation also means that the optimisation takes only a few seconds. This makes the procedure fast, convenient, and easy to use. An important application of this method is at the final stage of the implementation of theoretically designed pulse shapes: compensation of pulse distortions introduced by the instrument. The performance is illustrated using spin echo and out-of-phase electron spin echo envelope modulation experiments. Interface code between Bruker SpinJet arbitrary waveform generator and Matlab is included in versions 2.2 and later of the Spinach library.
ESR, AWG, feedback control , spin echo, OOP-ESEEM
1090-7807
9-16
Goodwin, David L.
349b642d-bc15-4a8d-b1d7-98691a39e069
Myers, William K.
0c67d834-c886-449c-9bb2-7beb68487332
Timmel, Christiane R.
e0ae17b0-5dc2-46b8-94ba-1fd2c0481e8c
Kuprov, Ilya
bb07f28a-5038-4524-8146-e3fc8344c065
Goodwin, David L.
349b642d-bc15-4a8d-b1d7-98691a39e069
Myers, William K.
0c67d834-c886-449c-9bb2-7beb68487332
Timmel, Christiane R.
e0ae17b0-5dc2-46b8-94ba-1fd2c0481e8c
Kuprov, Ilya
bb07f28a-5038-4524-8146-e3fc8344c065

Goodwin, David L., Myers, William K., Timmel, Christiane R. and Kuprov, Ilya (2018) Feedback control optimisation of ESR experiments. Journal of Magnetic Resonance, 297, 9-16. (doi:10.1016/j.jmr.2018.09.009).

Record type: Article

Abstract

Numerically optimised microwave pulses are used to increase excitation efficiency and modulation depth in electron spin resonance experiments performed on a spectrometer equipped with an arbitrary waveform generator. The optimisation procedure is sample-specific and reminiscent of the magnet shimming process used in the early days of nuclear magnetic resonance – an objective function (for example, echo integral in a spin echo experiment) is defined and optimised numerically as a function of the pulse waveform vector using noise-resilient gradient-free methods. We found that the resulting shaped microwave pulses achieve higher excitation bandwidth and better echo modulation depth than the pulse shapes used as the initial guess. Although the method is theoretically less sophisticated than simulation based quantum optimal control techniques, it has the advantage of being free of the linear response approximation; rapid electron spin relaxation also means that the optimisation takes only a few seconds. This makes the procedure fast, convenient, and easy to use. An important application of this method is at the final stage of the implementation of theoretically designed pulse shapes: compensation of pulse distortions introduced by the instrument. The performance is illustrated using spin echo and out-of-phase electron spin echo envelope modulation experiments. Interface code between Bruker SpinJet arbitrary waveform generator and Matlab is included in versions 2.2 and later of the Spinach library.

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AWG ESR Feedback Control - Accepted Manuscript
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Accepted/In Press date: 21 September 2018
e-pub ahead of print date: 28 September 2018
Published date: December 2018
Keywords: ESR, AWG, feedback control , spin echo, OOP-ESEEM

Identifiers

Local EPrints ID: 425080
URI: http://eprints.soton.ac.uk/id/eprint/425080
ISSN: 1090-7807
PURE UUID: 416e1fef-e45c-4cf3-861f-d96012a3accf
ORCID for Ilya Kuprov: ORCID iD orcid.org/0000-0003-0430-2682

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Date deposited: 10 Oct 2018 16:30
Last modified: 15 Sep 2021 04:57

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Contributors

Author: David L. Goodwin
Author: William K. Myers
Author: Christiane R. Timmel
Author: Ilya Kuprov ORCID iD

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