Dimitrov I E, Reddy R, Leigh J S
Department of Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia 19104, USA.
J Magn Reson. 2000 Aug;145(2):302-6. doi: 10.1006/jmre.2000.2097.
Intermolecular (129)Xe-(1)H nuclear Overhauser effects and (129)Xe longitudinal relaxation time measurements were used to demonstrate that the dipole-dipole coupling is the dominant relaxation mechanism for (129)Xe in water, at room temperature. (129)Xe-(1)H cross-relaxation rates were derived to be sigma(XeH) approximately 3.2 +/- 0.3 x 10(-3) s(-1), independent of xenon pressure (in the range of 1-10 bar) and of the presence of oxygen. Corresponding xenon-proton internuclear distances were calculated to be 2.69 +/- 0.12 A. Using the magnitude of the dipole-dipole coupling and the spin density ratio between dissolved xenon and bulk water, it is estimated that (129)Xe-(1)H spin polarization-induced nuclear Overhauser effects would yield little net proton signal enhancement in water.
利用分子间（129）Xe - （1）H核Overhauser效应和（129）Xe纵向弛豫时间测量结果，证明在室温下，偶极 - 偶极耦合是水中（129）Xe的主要弛豫机制。得出（129）Xe - （1）H交叉弛豫率为σ(XeH)约3.2±0.3×10⁻³ s⁻¹，与氙气压力（1 - 10 bar范围内）和氧气的存在无关。计算出相应的氙 - 质子核间距为2.69±0.12 Å。利用偶极 - 偶极耦合的大小以及溶解氙与大量水之间的自旋密度比，估计（129）Xe - （1）H自旋极化诱导的核Overhauser效应在水中产生的净质子信号增强很小。
