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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >NMR Study on the Reorientational Relaxation in Supercritical Alcohols
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NMR Study on the Reorientational Relaxation in Supercritical Alcohols

机译：核磁共振研究超临界醇中的重排弛豫

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摘要

The single-molecular reorientational relaxation of supercritical deuterated methanol and ethanol is studied by the ~2H nuclear magnetic resonance spin-lattice relaxation measurement,and the results are compared with the corresponding study on supercritical water (Matubayasi,N.;Nakao,N.;Nakahara,M.J.Chem.Phys.2001,114,4107).The relaxation times of the OD deuterons of both alcohols show significant increase when they are transferred from liquid to supercritical phases.The reorientational relaxation of the OD vector is thus largely enhanced in the supercritical phase,as is the case of water.The relative increase in the reorientational relaxation rates of alcohols with density is larger than that of water.It indicates that the reorientational motion of supercritical alcohols is more diffusive than that of water.The molecular dynamics simulation of the supercritical methanol is also performed,and the results are consistent with experimental ones.The reorientational relaxation of two deuterated solute molecules,benzene (C_6D_6) and pyrazine (C4D_4N_2),is studied in supercritical methanol in addition to the neat fluid.The density dependence of the ~2H spin-lattice relaxation rates of methanol,benzene,and pyrazine in supercritical methanol show a minimum.The density of the minimum relaxation rate decreases with increasing solute-solvent interaction,which can be explained in terms of the angular-momentum relaxation time.
机译：通过〜2H核磁共振自旋晶格弛豫测量研究了超临界氘化甲醇和乙醇的单分子方向性弛豫，并将结果与​​超临界水的相应研究进行了比较（Matubayasi，N。; Nakao，N .; Nakahara，MJChem.Phys.2001,114,4107）。当两种醇的OD氘代从液相转移到超临界相时，其OD氘的弛豫时间显着增加，因此OD载体的方向性弛豫在很大程度上得以增强。超临界相，例如水。密度较大的醇的重取向弛豫速率的相对增加幅度要大于水。这表明超临界醇的重取向弛豫运动比水更具有扩散性。分子动力学模拟还进行了超临界甲醇的合成，结果与实验结果相符。除纯净流体外，还研究了超临界甲醇中的溶质分子苯（C_6D_6）和吡嗪（C4D_4N_2）。甲醇，苯和吡嗪在超临界甲醇中〜2H自旋晶格弛豫速率的密度依赖性表明：最小弛豫速率的密度随着溶质-溶剂相互作用的增加而降低，这可以用角动量弛豫时间来解释。

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