Reorientation dynamics in liquid alcohols from Raman spectroscopy
Reorientation dynamics in liquid alcohols from Raman spectroscopy
复制标题
拉曼光谱中液体醇的重新取向动力学
DOI：
10.1002/jrs.2997
复制
发表时间：
2012-01-01
影响因子：
2.5
通讯作者：
Luo, Yi
中科院分区：
文献类型：
--
作者：
Lin, Ke;Hu, Naiyin;Luo, Yi
偏振拉曼光谱已被用于研究纯液体和水溶液中醇分子的再取向，或更具体地说，平移弛豫动力学。从光谱宽度测量中发现，纯液体中的醇分子通常具有皮秒量级的平移弛豫时间，遵循甲醇<乙醇<异丙醇<正丙醇的顺序。温度依赖性的测量表明，氢键（HB）和疏水相互作用控制的平移运动。考虑到CH 3基团，疏水相互作用比骨架运动更明显地减少弛豫时间。对于醇-水混合物，水浓度的增加通常以非单调行为减缓弛豫过程。然而，当酒精浓度进一步下降时，这种趋势在某一点停止，酒精分子的运动变得更快。人们提出了不同的机制来解释这些观察结果，这可能有助于更深入地了解醇与水的HB网络。我们的研究有力地说明了拉曼光谱可以应用于HB系统中分子的快速平移运动的研究。版权所有© 2011约翰威利父子有限公司.
Polarized Raman spectroscopy has been employed to study the reorientational, or more specifically the translational relaxation dynamics, of alcohol molecules in pure liquids and aqueous solutions. It is found from the spectral width measurements that alcohol molecules in pure liquids have typically translational relaxation times on the order of picoseconds, following the order methanol < ethanol < i-propanol < n-propanol. Temperature-dependent measurements show that hydrogen-bonding (HB) and hydrophobic interactions control the translational motion. The hydrophobic interaction reduces the relaxation time more apparently in view of the CH3 group than the skeleton motion. For alcohol–water mixtures, the increase of water concentration generally slows down the relaxation process in a non-monotonic behavior. However, the trend stops at a certain point and the motion of alcohol molecules becomes faster when the alcohol concentration further drops. Different mechanisms have been proposed to interpret these observations, which might be helpful to gain deeper insight into the HB networks of alcohols with water. Our study strongly illustrates that Raman spectroscopy can be applied to the study of fast translational motion of molecules in HB systems. Copyright © 2011 John Wiley & Sons, Ltd.