Nuclear Magnetic Relaxation of 1H in the Organic Radical Salts m-MPYNN+·ClO 4- and m-MPYNN+·BF 4-
Nuclear Magnetic Relaxation of 1H in the Organic Radical Salts m-MPYNN+·ClO 4- and m-MPYNN+·BF 4-
复制标题
有机自由基盐m-MPYNN+·ClO 4- 和m-MPYNN+·BF 4- 中1H的核磁弛豫
DOI：
10.1143/jpsj.69.1294
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发表时间：
2000
影响因子：
1.7
通讯作者：
K. Awaga
中科院分区：
文献类型：
--
作者：
Y. Fujii;T. Goto;A. Oyamada;T. Okuno;K. Awaga
我们测量了有机盐m -MPYNN + ·ClO 4 - 和m -MPYNN + ·BF 4 - 在2 K 和100 K 温度范围内高达70 kOe 的外场下1 H 的核自旋晶格弛豫时间T 1 。在这些盐中，由于铁磁相互作用 J 1 ，两个阳离子（自旋 1/2）自由基构成二聚体。我们根据铁磁二聚体能级的两个弛豫过程解释了 T 1 -1 低于约 10 K (∼ J 1 / k B ) 的实验结果。由纵向和横向自旋波动引起的触发器和直接过程分别在较高场和较低场中占主导地位，交叉场约为 10 kOe。对于较高温度下T 1 -1 的场依赖性，二维系统中自旋1/2的自旋扩散模型得到了令人满意的应用。
We have measured nuclear spin-lattice relaxation times T 1 of 1 H in the organic salts m -MPYNN + ·ClO 4 - and m -MPYNN + ·BF 4 - in the temperature range between 2 K and 100 K under external fields up to 70 kOe. In these salts, two cationic (spin-1/2) radicals constitute a dimer due to the ferromagnetic interaction J 1 . We interpreted the experimental results of T 1 -1 below about 10 K (∼ J 1 / k B ) in terms of two relaxation processes based on the energy levels of the ferromagnetic dimer. The flip-flop and the direct processes which are due to longitudinal and transverse spin fluctuations become dominant at higher and lower fields, respectively, the crossover field being around 10 kOe. For the field dependence of T 1 -1 at higher temperatures, the spin diffusive model of spin-1/2 in a two-dimensional system is satisfactorily applied.