NMR of platinum catalysts. II. Relaxation
NMR of platinum catalysts. II. Relaxation
复制标题
铂催化剂的核磁共振。
DOI：
10.1103/physrevb.26.3569
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发表时间：
1982
影响因子：
3.7
通讯作者：
J. Sinfelt
中科院分区：
文献类型：
--
作者：
H. Rhodes;P. Wang;C. D. Makowka;S. Rudaz;H. Stokes;C. Slichter;J. Sinfelt
作者报道了在氧化铝上负载的小颗粒Pt的自旋-晶格弛豫时间T1和自旋-自旋弛豫时间T2的测量。T1和T2是在不同的静态场Hp，频率Vp为45，55和74 MHz，温度为4.2，77和300 K下测量的。尽管在任何给定的Vp下Hp/Vp都是强函数，但在固定Hp/Vp下的弛豫时间T1和T2与颗粒尺寸无关。Tl在对应于论文I（前一篇论文）中描述的“表面峰”的位置（Hp/Vp）处最长，表明传导电子自旋在很大程度上与表面Pt原子捆绑在一起。T1中的峰随着表面涂层的变化而移动位置，正如NMR回波振幅中的峰一样，这表明作为表面涂层的函数的表面峰的Hp/vp的变化很可能是化学位移。
The authors report measurement of ' Pt spin-lattice relaxation times Tl and spin-spin relaxation times T2 of small particles of Pt supported on alumina. Tl and T2 were measured at various static fields H p, for frequencies vp of 45, 55, and 74 MHz, and at temperatures of 4.2, 77, and 300 K. Though strong functions of H p/vp at any given vp, the relaxation times Tl and T2 at fixed Hp/vp are independent of particle size. Tl is longest at the position (Hp/vp) corresponding to the "surface peak" described in paper I (the preceding paper), indicating that conduction-electron spins are largely tied up for surface Pt atoms. The peak in Tl shifts position with change in surface coating exactly as does the peak in NMR echo amplitude, showing that the change in Hp/vp of the surface peak as a function of surface coating is most likely a chemical shift.