Infrared spectroscopic probing of dimethylamine clusters in an Ar matrix

作     者：Siyang Li Henrik G.Kjaergaard Lin Du 

作者机构：Environment Research Institute Shandong University Shanda South Road 27 Shandong 250100 China Department of Chemistry University of Copenhagen Universitetsparken 5 DK-2100 Copenhagen φ Denmark 

出 版 物：《Journal of Environmental Sciences》 (环境科学学报（英文版）)

年 卷 期：2016年第28卷第2期

页      面：51-59页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 07[理学] 08[工学] 070602[理学-大气物理学与大气环境] 0706[理学-大气科学] 0713[理学-生态学] 

基　　金：supported by the Danish Council for Independent Research-Natural Sciences,the Danish Center for Scientific Computing (DCSC) National Natural Science Foundation of China (Nos.21407095,21577080) Shandong Provincial Natural Science Foundation,China (No.ZR2014BQ013) 

主　　题：Matrix isolation Infrared(IR) spectroscopy Dimethylamine clusters Aerosol nucleation 

摘      要：Amines have many atmospheric sources and their clusters play an important role in aerosol nucleation processes. Clusters of a typical amine, dimethylamine（DMA）, of different sizes were measured with matrix isolation IR（infrared） and NIR（near infrared）spectroscopy. The NIR vibrations are more separated and therefore it is easier to distinguish different sizes of clusters in this region. The DMA clusters, up to DMA tetramer, have been optimized using density functional methods, and the geometries, binding energies and thermodynamic properties of DMA clusters were obtained. The computed frequencies and intensities of NH-stretching vibrations in the DMA clusters were used to interpret the experimental spectra. We have identified the fundamental transitions of the bonded NH-stretching vibration and the first overtone transitions of the bonded and free NH-stretching vibration in the DMA clusters. Based on the changes in vibrational intensities during the annealing processes, the growth of clusters was clearly observed. The results of annealing processes indicate that DMA molecules tend to form larger clusters with lower energies under matrix temperatures, which is also supported by the calculated reaction energies of cluster formation.