海盐气溶胶界面有机膜的红外光谱研究  

Infrared spectroscopy study of interfacial organic film of sea salt aerosol

作　　者：程淑敏 杜林 CHENG Shumin;DU Lin(Environment Research Institute,Shandong University,Qingdao 266237,China)

机构地区：[1]山东大学环境研究院,山东青岛266237

出　　处：《大气与环境光学学报》2022年第1期171-184,共14页Journal of Atmospheric and Environmental Optics

基　　金：国家自然科学基金,21876098。

摘　　要：海盐气溶胶(SSA)是海洋与大气进行物质交换的重要媒介。表面活性有机物是SSA界面有机膜的重要组成部分。有机膜的组分和形态变化对SSA的物理、化学和光学特性有着重要的影响,进而改变SSA的大气过程。将Langmuir槽与红外反射吸收光谱(IRRAS)技术相结合,从宏观角度和微观层面综合监测了表面膜的分子排布和构象信息。以水-气界面的硬脂酸/油酸和硬脂酸/反油酸复合组分单分子膜体系为例,研究了SSA界面上长链脂肪酸分子之间的相互作用,并探究了不饱和度和双键构型对复合膜界面特性的影响。研究发现,相对于trans双键构型的反油酸,油酸分子在cis构型双键位置的弯曲和折叠致使其具有更大的空间位阻,这使得它在单分子膜的挤压过程中会更大程度地阻碍硬脂酸分子的紧密排列。Sea salt aerosol(SSA) is an important link between ocean and atmosphere. Surface-active organics constitute a major fraction of the organic film of SSA. It is believed that the changes in chemical composition and surface organization of the organic film have important influences on physical, chemical and optical properties of SSA, and then affect many atmospheric processes. A Langmuir trough was used in combination with infrared reflection absorption spectroscopy(IRRAS) to detect the molecular arrangement of the surface film from macroscopic viewpoints as well as microscopic consideration. Focusing on the mixed monolayers of stearic acid/oleic acid(OA)and stearic acid/elaidic acid(EA) at the air-water interface, the intermolecular interactions between long-chain fatty acids at the SSA interface were investigated, and the effects of saturation degree and double bond configuration of organics on the surface properties of SSA were clarified. It is found that compared with EA with trans-double bond, the obstructive effect on the molecular ordering was found to be significantly remarkable for OA where the cis-double bond exists in the middle of molecular chain. Although the trans-double bond in the alkyl chain of EA also produces the obstruction, the degree is not as much as that caused by the cis-one.

关 键 词：单分子膜 海盐气溶胶 界面特性 水-气界面 大气过程 

分 类 号：X131.1[环境科学与工程—环境科学]