Multiple-pulse NMR experiments are a powerful tool for the investigation of mole- cules with coupled nuclear spins. The product operator formalism provides a way to understand the quantum evolution of an ensemble of weakly coupled spins in such experiments using some of the more intuitive concepts of classical physics and semi- classical vector representations. In this paper I present a new way in which to inter- pret the quantum evolution of an ensemble of spins. I recast the quantum problem in terms of mixtures of pure states of two spins whose expectation values evolve identi- cally to those of classical moments. Pictorial representations of these classically evolving states provide a way to calculate the time evolution of ensembles of weakly coupled spins without the full machinery of quantum mechanics, offering insight to anyone who understands precession of magnetic moments in magnetic fields.
Concepts in Magnetic Resonance: Part A
Physics & Astronomy
Recommendation from the publisher. How to cite this article: Ligare M. Manifestations of classical physics in the quantum evolution of correlated spin states in pulsed NMR experiments. Concepts Magn Reson Part A. 2017;45A:e21398. https://doi.org/10.1002/cmr.a.21398