12: Lecture 12: A Relaxation Theory of Nuclear Spin States
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Published:13 Jun 2022
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Special Collection: RSC eTextbook CollectionProduct Type: Textbooks
Lectures On Spin Dynamics: The Theoretical Minimum, The Royal Society of Chemistry, 2022, pp. 143-162.
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In this lecture, I discuss a semi-classical relaxation theory of nuclear spin states, the so-called Wangsness–Bloch–Redfield (WBR) theory. I first discuss the concept of relaxation to an equilibrium configuration in a qualitative manner, in order to introduce the two most important relaxation decay constants: T 1 and T 2. Later, I derive a compact expression for the dynamics under incoherent Hamiltonians, define its validity regime and introduce the concept of a relaxation superoperator. Finally, the dipolar contribution to the relaxation superoperator is derived and put to use to calculate the longitudinal and transverse relaxation decay rate constants due to such a mechanism.