Hommel Elizabeth L, Allen Heather C
Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210.
J Phys Chem B. 2003 Oct 2;107(39):10823-8. doi: 10.1021/jp027830e.
Vibrational broad bandwidth sum frequency generation spectroscopy was employed to investigate the surface structure of neat 1-methyl naphthalene (1-MN) and the reorientation of the 1-MN molecules upon saturation of the 1-MN liquid with water. The neat 1-MN liquid molecules have their aromatic rings aligned antiparallel to one another with their methyl groups alternating out of the surface and into the subsurface region from molecule to molecule. With the introduction of relatively few water molecules into the 1-MN liquid (1:336 water/1-MN) a rearrangement of the surface molecules is induced, leading to an increased number density of the methyl groups arranged such that more methyl groups are oriented in the same direction into the air phase at the air-liquid 1-MN interface. Surface tension measurements reveal an increase in the surface tension upon water saturation of the 1-MN liquid, indicating surface activity of the water in the 1-MN solution. It is also clear that the reorientation of the surface 1-MN molecules is reversible.
采用振动宽带和频产生光谱法研究了纯1-甲基萘（1-MN）的表面结构以及1-MN液体被水饱和后1-MN分子的重新取向。纯1-MN液体分子的芳香环彼此反平行排列，其甲基在分子间交替地从表面伸出并进入次表面区域。向1-MN液体中引入相对较少的水分子（水/1-MN = 1:336）会诱导表面分子发生重排，导致甲基排列的数密度增加，使得更多甲基在气-液1-MN界面处沿相同方向朝向气相。表面张力测量结果表明，1-MN液体被水饱和后表面张力增加，这表明水在1-MN溶液中具有表面活性。同样明显的是，表面1-MN分子的重新取向是可逆的。
