外电场对溴苯分子光谱特征影响的研究  

Effect of External Electric Field on the Spectral Characteristics of Bromobenzene

作　　者：陈宇[1] 刘玉柱[1,2] 王兴晨 布玛丽亚·阿布力米提 CHEN Yu;LIU Yu-zhu;WANG Xing-chen;ABULIMITI Bumaliya(Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean,Nanjing University of Information Science&Technology,Nanjing 210044,China;Shanghai Qizhi Institute,Shanghai 200232,China;College of Physics and Electronic Engineering,Xinjiang Normal University,Urumqi 830054,China)

机构地区：[1]江苏省大气海洋光电探测重点实验室(南京信息工程大学),江苏南京210044 [2]上海期智研究院,上海200232 [3]新疆师范大学物理与电子工程学院,新疆乌鲁木齐830054

出　　处：《光谱学与光谱分析》2020年第12期3732-3735,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(U1932149);江苏省自然科学基金项目(BK20191395);江苏省高等学校自然科学研究项目(18KJA140002)资助。

摘　　要：芳香族化合物是一类广泛存在于自然界的性质稳定、具有很大毒性和致癌、致畸性的化学物质。其中,溴苯(C6H5Br)是破坏自然环境并对人类身体健康有严重威胁的有机污染物之一,研究外电场对溴苯光谱特征的影响在大气化学、燃烧化学、环境监测等领域有很广泛的应用。基于密度泛函理论(density functional theory, DFT),在BPV86/6-311G(d, p)水平上计算优化得到了不同外加电场(0~0.03 a.u.)下,溴苯分子的红外光谱。并在此基础上,用同样的基组计算优化得到了溴苯分子的紫外-可见吸收(UV-Vis)光谱。在实际测量过程存在诸多困难,很难得到特定大小和方向电场下溴苯分子的红外光谱、 UV-Vis光谱等物理特性。研究表明:通过与实验值比较,基于密度泛函理论计算得到的溴苯的红外光谱和UV-Vis光谱具有很高的准确度和很好的分辨率,且包含的波长范围更广。因此这些结果可作为实验值的补充,为在理论上研究外电场对溴苯分子C-Br键振动频率、红外光谱和UV-Vis光谱的影响提供了新的方法和思路,具有很强的参考价值。无外电场情况下,由于C-H键振动,溴苯分子的红外光谱在频率为718 cm^-1处出现了最强吸收峰,在1 455 cm^-1处产生了一个仅次于最强峰的吸收峰。C-Br键在727和1 185 cm^-1附近有两个较强的吸收峰。随着外电场从0增大到0.03a.u., C—Br键的两个红外光谱特征峰均发生不同程度的红移且振动强度增大,部分C-H键振动也有类似的变化。电荷沿C-Br键从6C原子转移到Br原子,大大增强了Br原子的电负性, 6C原子的负电荷密度略有降低。因此, 6C原子和Br原子之间的库仑力增大,导致C-Br键红外光谱的振动强度增大。同时, UV-Vis光谱最强峰对应的波长从191.6 nm蓝移到187.4 nm,摩尔吸收系数从23 402.171增大到28 885.125。这些结果为研究溴苯在外电场下的光谱检测提供了理论参考,也对研究其他有Aromatic compounds are widely existing in nature.They are stable,highly toxic,carcinogenic and teratogenic chemicals.Among them,bromobenzene(C 6H 5Br)is one of the organic pollutants that damage the natural environment and pose a serious threat to human health.The study of the influence of external electric field on the spectrum of bromobenzene has been widely used in atmospheric chemistry,combustion chemistry,environmental monitoring and other fields.In the present paper,density functional theory(DFT)at BPV86/6-311G(d,p)level are employed for the study of IR spectrum of bromobenzene in the external electric field.Based on the density functional theory,the UV-Vis spectra of bromobenzene molecules are obtained by the same method and basis set.In the actual measurement,it is difficult to obtain physical characteristics such as the infrared spectrum and UV-Vis spectrum of bromobenzene molecules under an electric field of a specified size and direction.The research shows that by comparing with the experimental values,the infrared spectrum and UV-Vis spectrum of bromobenzene calculated based on density functional theory have high accuracy and good resolution,and include a wider range of wavelengths.Therefore,these results can be used as a supplement to the experimental values,which provides a new method for theoretically studying the influence of the external electric field.Without the external electric field,due to the C—H bond vibration,the infrared spectrum of bromobenzene molecule has the strongest absorption peak at a wave number of 718 cm-1,and an absorption peak with an intensity second only to the strongest peak at 1455 cm-1.The C—Br bond has two strong absorption peaks near 727 and 1185 cm-1.As the external electric field increases from 0 to 0.03 a.u.,both infrared absorption peaks of the C—Br bond are red-shifted and the vibration intensity increases,C—H bond vibrations have similar changes.The charge transfers the Br atom from the 6C atom along with the C—Br bond,which greatly enhances the electro

关 键 词：溴苯 密度泛函理论 红外光谱 紫外-可见吸收光谱 

分 类 号：O433.4[机械工程—光学工程]