Cross-Effect Dynamic Nuclear Polarization Explained: Polarization, Depolarization, and Oversaturation.

作者：A. Equbal, Alisa Leavesley, S. Jain, Songi Han · 发表于：Journal of Physical Chemistry Letters · 年份：2019 · DOI：10.1021/acs.jpclett.8b02834 · 被引用次数：39 · 研究领域：Medicine、Physics

The scope of this Perspective is to analytically describe NMR hyperpolarization by the three-spin cross effect (CE) dynamic nuclear polarization (DNP) using an effective Hamiltonian concept. We apply, for the first time, the bimodal operator-based Floquet theory in the Zeeman-interaction frame for two and three coupled spins to derive the known interaction Hamiltonian for CE-DNP. With a unified understanding of CE-DNP, and supported by empirical observation of the state of electron spin polarization under the given experimental conditions, we explain diverse manifestations of CE from oversaturation, enhanced hyperpolarization by broad-band saturation, to nuclear spin depolarization under magic-angle spinning.