Bahçeli S, Klinowski J
Department of Chemistry, University of Cambridge, UK.
Solid State Nucl Magn Reson. 1993 Oct;2(5):269-78. doi: 10.1016/0926-2040(93)90008-b.
Transverse relaxation times in the rotating frame of quadrupolar nuclei with half-integer spins are inversely proportional to the linewidth of quadrupole nutation NMR spectra. We apply fictitious spin -1/2 operators to I = 3/2 nuclei to derive correlations between the transitions of a multi-level system which affect nuclear relaxation. When omega rf << omega Q, all possible multiple-quantum transitions contribute to the transverse quadrupolar relaxation time in the rotating frame T2Qp. When omega rf >> omega Q, two of the three single-quantum transitions do not contribute. In the low-temperature region (outside the extreme narrowing limit), the contribution of double- and triple-quantum coherences to T2Qp goes through a minimum for omega rf << omega Q, while the triple-quantum coherence appears at zero frequency and corresponds to a short transverse relaxation time for omega rf >> omega Q.
具有半整数自旋的四极核在旋转坐标系中的横向弛豫时间与四极章动核磁共振谱的线宽成反比。我们将虚拟自旋-1/2算符应用于I = 3/2核，以推导影响核弛豫的多能级系统跃迁之间的相关性。当ωrf << ωQ时，所有可能的多量子跃迁都会对旋转坐标系中的横向四极弛豫时间T2Qp产生贡献。当ωrf >> ωQ时，三个单量子跃迁中的两个不产生贡献。在低温区域（极端窄化极限之外），对于ωrf << ωQ，双量子和三量子相干对T2Qp的贡献经历一个最小值，而对于ωrf >> ωQ，三量子相干出现在零频率处，对应于较短的横向弛豫时间。
