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中国科学院大学学报 ›› 2018, Vol. 35 ›› Issue (6): 839-844.DOI: 10.7523/j.issn.2095-6134.2018.06.016

• 简报 • 上一篇    下一篇

碘甲烷在外电场下的光谱和解离特性

张翔云1, 刘玉柱1,2, 马馨宇1, 秦朝朝3   

  1. 1 南京信息工程大学 江苏省大气海洋光电探测重点实验室, 南京 210044;
    2 江苏省大气环境与装备技术协同创新中心, 南京 210044;
    3 河南师范大学物理与材料科学学院, 河南 新乡 453007
  • 收稿日期:2017-07-20 修回日期:2017-09-12 发布日期:2018-11-15
  • 通讯作者: 刘玉柱
  • 基金资助:
    Supported by Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(18KJA140002), Six Talent Peaks Project in Jiangsu Province(2015-JNHB-011), College Students Practice Innovative Tranining Program of Nuist(201710300058Y), and Undergraduate Training Program for Innovation and Entrepreneurship(201710762008,201710762055)

Dissociation and physical properties of methyl iodide in external electric field

ZHANG Xiangyun1, LIU Yuzhu1,2, MA Xinyu1, QIN Chaochao3   

  1. 1 Jiangsu key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of Information Science & Technology, Nanjing 210044, China;
    2 Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology(CICAEET), Nanjing 210044, China;
    3 College of Physics and Materials Science, Henan Normal University, Xinxiang 453007, Henan, China
  • Received:2017-07-20 Revised:2017-09-12 Published:2018-11-15
  • Supported by:
    Supported by Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(18KJA140002), Six Talent Peaks Project in Jiangsu Province(2015-JNHB-011), College Students Practice Innovative Tranining Program of Nuist(201710300058Y), and Undergraduate Training Program for Innovation and Entrepreneurship(201710762008,201710762055)

摘要: 碘甲烷是一种有毒的甲基化试剂和土壤消毒剂,应用十分广泛,研究其基本的物理性质和使其降解的有效措施很有必要。使用密度泛函理论(density functional theory,DFT),在B3LYP/LANL2DZ水平上研究在外电场(0~0.04a.u.)作用下碘甲烷分子的解离特性以及多种物理性质。计算结果表明,在C—I键连线Z方向上,外电场从0逐渐增加到0.04a.u.时,分子体系能量逐渐减小,偶极矩单调增大.HOMO-LUMO能隙EG却呈现先增大后减小的变化趋势,C—I和C—H键键长逐渐增大,更加易于裂解。在外电场逐渐增强时,解离特性表现为:CH3I分子的C—I键方向扫描得到的势能曲线的束缚状态逐渐消失,势垒逐渐变小最后消失。计算发现,强度为0.04a.u.的外电场足以使CH3I分子发生C—I键断裂而降解。该结果为保护环境和对碘甲烷进行电场降解提供理论依据。

关键词: 碘甲烷, 外电场, 降解, 红外光谱

Abstract: As a kind of toxic methylation reagent and disinfectant, methyl iodide (CH3I) is widely used. It is important to study the basic physical properties of methyl iodide and to use effective measures to degrade it. The ground states of methyl iodide in different electric fields from 0 to 0.04a.u.(atomic unit) are optimized using the B3LYP calculation with the LANL2DZ basis set. Optimized parameters, total energies, bond lengths, dipole moments, the highest occupied molecular orbital energies, the lowest unoccupied molecular orbital energies, energy gaps, infrared spectra, and dissociation potential energy surface (PES) are obtained. The obtained results show that when the external electric field gradually increases from 0 to 0.04a.u. along the molecular axis Z (the C-I bond direction), the total energy decreases while the dipole moment increases. The C-I and C-H bond lengths increase gradually. The energy gap first increases and then decreases with the external electric field. Further studies show that when the external electric field increases from 0 to 0.04 a.u., the dissociation PES along the C-I bond becomes unbound with the potential energy barrier disappearing. The external electric field of 0.04 a.u. is sufficient to induce the degradation of methyl iodide with the C-I bond breaking. This work provides an important support for the degradation of methyl iodide in the external electric field.

Key words: methyl iodide, external electric field, degradation, infrared spectrum

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