TY - CHAP

T1 - Chapter 9

T2 - Manipulating Singlet Order with Adiabatic Pulses

AU - Kiryutin, Alexey S.

AU - Rodin, Bogdan A.

AU - Lukzen, Nikita N.

AU - Yurkovskaya, Alexandra V.

AU - Vieth, Hans Martin

AU - Ivanov, Konstantin L.

N1 - Financial support from the Russian Science Foundation (grant No. 19-43-04116) is gratefully acknowledged.

PY - 2020

Y1 - 2020

N2 - A family of methods is introduced for creating, manipulating and observing nuclear singlet spin order. The basic element is conversion between longitudinal magnetisation and singlet spin order, M2S and S2M. It is based on near-resonance radio-frequency pulses of adiabatically varying amplitude that guide the spins through regions of avoided level-crossings of the system. After discussing the theoretical concepts, we illustrate the practical application of such Adiabatic Passage Spin Order Conversion (APSOC) by analysing the relaxation decay of singlet order independent of the coupling strength of the spin pair. By combining several such pulse sequences and varying their carrier frequency, a filter is designed for Singlet Order Selection (SOS) and suppression of all other spectral components. It enables background-free detection of selected spin pairs. To ease the constraint of slow amplitude variation while staying within the limits of adiabaticity the pulse amplitude profile is shaped so that only near level-crossings speed is reduced, but increased elsewhere; optimum control methods are used to find the ideal pulse shape. In this way adverse relaxation effects during pulses are minimised. Conversion factors close to the theoretical maximum are thus achievable. With such a toolbox not only highly efficient conversion is possible, but also other manipulations of spin order, e.g. polarisation transfer between different spin species or anti-phase to in-phase transformation of spectral components.

AB - A family of methods is introduced for creating, manipulating and observing nuclear singlet spin order. The basic element is conversion between longitudinal magnetisation and singlet spin order, M2S and S2M. It is based on near-resonance radio-frequency pulses of adiabatically varying amplitude that guide the spins through regions of avoided level-crossings of the system. After discussing the theoretical concepts, we illustrate the practical application of such Adiabatic Passage Spin Order Conversion (APSOC) by analysing the relaxation decay of singlet order independent of the coupling strength of the spin pair. By combining several such pulse sequences and varying their carrier frequency, a filter is designed for Singlet Order Selection (SOS) and suppression of all other spectral components. It enables background-free detection of selected spin pairs. To ease the constraint of slow amplitude variation while staying within the limits of adiabaticity the pulse amplitude profile is shaped so that only near level-crossings speed is reduced, but increased elsewhere; optimum control methods are used to find the ideal pulse shape. In this way adverse relaxation effects during pulses are minimised. Conversion factors close to the theoretical maximum are thus achievable. With such a toolbox not only highly efficient conversion is possible, but also other manipulations of spin order, e.g. polarisation transfer between different spin species or anti-phase to in-phase transformation of spectral components.

UR - http://www.scopus.com/inward/record.url?scp=85089892994&partnerID=8YFLogxK

UR - https://elibrary.ru/item.asp?id=45360385

U2 - 10.1039/9781788019972-00169

DO - 10.1039/9781788019972-00169

M3 - Chapter

AN - SCOPUS:85089892994

SN - 978-1-78801-568-4

T3 - New Developments in NMR

SP - 169

EP - 187

BT - Long-lived Nuclear Spin Order

A2 - Pileio, Giuseppe

PB - Royal Society of Chemistry

ER -