Chapter 3: Relaxation Theory of Long-lived Spin Order
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Published:07 Apr 2020
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Special Collection: 2020 ebook collectionSeries: New Developments in NMR
G. Pileio, in Long-lived Nuclear Spin Order: Theory and Applications, ed. G. Pileio, The Royal Society of Chemistry, 2020, ch. 3, pp. 64-91.
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This chapter discusses several relaxation mechanisms that contribute to the relaxation decay rate of singlet and longitudinal order. In a systematic approach I use the Redfield theory to obtain analytical equations for these contributions. The mechanisms that occur in isolated two-spin-1/2 pairs are discussed first and apply to cases where the singlet pair is the only spin system in the molecule. When other spins are present, other mechanisms may arise and some of these are discussed below. Finally, coherent leakage mechanisms that contribute to singlet but not to longitudinal order relaxation decay rates are introduced and discussed.