Effect of pressure on local order in liquid dimethyl sulfoxide
Effect of pressure on local order in liquid dimethyl sulfoxide
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DOI：
10.1021/jp984660q
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发表时间：
1999-04-29
影响因子：
2.9
通讯作者：
Jonas, J
中科院分区：
文献类型：
--
作者：
Czeslik, C;Jonas, J
利用拉曼光谱研究了纯液体二甲基亚砜（DMSO）的分子间相互作用、动力学和结构。各向同性和各向异性的光谱记录在SO伸缩振动区域在30和70摄氏度之间的温度和压力下高达2200巴。为了分离温度和密度效应，还在相同的温度和压力范围内测定DMSO的密度。通过分析各向同性和各向异性谱，测量了拉曼非符合效应。这个耦合参数反映了分子间的相互作用，表现出非线性的密度增加，但对温度相对不敏感。随着密度的增加，在一阶矩和形状的各向同性SO带的急剧变化被检测到。SO伸缩振动带向低波数移动。而其半高全宽随压力的增加而显著增加，各向同性SO伸缩带被分解为三个分量，它们在加压时表现出明显不同的强度变化。结果进行了讨论，在压力诱导形成更强的分子聚集体，导致在液体DMSO在高压下增强的局部秩序。在一般意义上，这项研究的结果提供了另一个例子，占主导地位的体积效应超过动力学效应的动态结构的液体。
Raman spectroscopy was used to study intermolecular interactions, dynamics and the structure of neat liquid dimethyl sulfoxide (DMSO). Isotropic and anisotropic spectra were recorded in the SO stretching vibration region at temperatures between 30 and 70 degrees C and under pressures up to 2200 bar. To separate the temperature and density effects, the density of DMSO was also determined over the same region of temperature and pressure. By analyzing the isotropic and anisotropic spectra, the Raman noncoincidence effect was measured. This coupling parameter which reflects intermolecular interactions exhibits a nonlinear increase with density but is relatively insensitive to temperature. With increasing density, drastic changes in the first moment and the shape of the isotropic SO band were detected. The SO stretching vibration band shifts to lower wavenumbers. whereas its full width at half-height increases significantly with increasing pressure, The isotropic SO stretching band is resolved into three components which show markedly different intensity changes upon pressurization. The results are discussed in terms of pressure-induced formation of stronger molecular aggregates leading to an enhanced local order in liquid DMSO at elevated pressures. In a general sense, the results of this study provide yet another example of the dominance of volume effects over kinetic effects on the dynamic structure of liquids.