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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Pressure and Temperature Effects on the Hydrogen-Bond Structures of Liquid and Supercritical Fluid Methanol
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Pressure and Temperature Effects on the Hydrogen-Bond Structures of Liquid and Supercritical Fluid Methanol

机译：压力和温度对液态和超临界流体甲醇氢键结构的影响

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The proton spin-lattice relaxation times and proton chemical shifts for the hydroxyl and methyl protons in methanol were measured at liquid and supercritical densities using capillary high-pressure NMR spectroscopy. The pressure range for the proton nuclear relaxation measurements was between 50 and 3500 bar over a temperature range of 298-573 K. The proton chemical shifts of methanol were investigated for a pressure range of 50-3500 bar and a temperature range of 298-773 K. Attempts were made to separate the contributions of the dipolar and spin-rotation interactions to the spin-relaxation processes at each thermodynamic condition over methanol densities ranging from liquid to supercritical fluid. An average number of hydrogen bonds per molecule in methanol and the apparent activation energy of the methyl group internal rotation have been extracted from the experimental relaxation data. The extracted quantities show a moderate pressure dependence in addition to temperature effects, which suggest that molecular packing effects on hydrogen-bonded methanol are important at higher pressures. A comparison between methanol and water at similar thermodynamic conditions was also made to obtain new insight into these two important supercritical solvents.
机译：使用毛细管高压NMR光谱在液体和超临界密度下测量甲醇中羟基和甲基质子的质子自旋晶格弛豫时间和质子化学位移。在298-573 K的温度范围内，质子核弛豫测量的压力范围为50至3500 bar。在50-3500 bar的压力范围和298-773的温度范围内，研究了甲醇的质子化学位移。 K.尝试在从液体到超临界流体的甲醇密度上，在每种热力学条件下，将偶极和自旋旋转相互作用对自旋松弛过程的贡献分开。从实验弛豫数据中提取了甲醇中每个分子的平均氢键数和甲基内部旋转的表观活化能。提取的量除显示温度效应外还显示出适度的压力依赖性，这表明在较高压力下对氢键合甲醇的分子堆积效应很重要。还对相似热力学条件下的甲醇和水进行了比较，以了解这两种重要的超临界溶剂。

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