Liu Yu-zhu, lI Xiang-hong, Wang Jun-feng, Guan Yue, Jin Feng, Qin Chao-chao
Guang Pu Xue Yu Guang Pu Fen Xi. 2017 Mar;37(3):679-84.
Halon-1301 (CF3Br) can make Br radicals with UV radiation, which poses a great threat to the ozone layer in the atmosphere. Necessary methods should be taken for the degradation of the exhausts of Halon-1301. In this paper, density functional (DFT) theory at B3LYP/6-311G++(d,p) level are employed for the study of dissociation properties and spectra of Halon-1301 in external electric field, including bond length, total energy, HOMO-LUMO energy gap, infrared spectra and dissociation potential energy surface (PES). The obtained results show that, with gradually increasing the external field from 0 to 0.03 a.u. along the molecular axis Z (C—Br bond direction), the total energy decreases, while the dipole moment decreases at the beginning and then increases. With the climbing of the field, HOMO-LUMO energy gap increases, and C—Br bond length increases while C—F bond length decreases. The variations of vibrational frequency and intensity of molecular IR spectra in external electric field are also investigated. Further studies show that with increasing the external electric field from 0 to 0.03 a.u., the dissociation PES along C—Br bond becomes unbound with disappearing of the barrier for the dissociation. The external electric field of 0.03 a.u. is sufficient to induce the degradation of CF3Br with C—Br bond breaking. Such results provide an important reference for the degradation of Halons via the external electric field.
哈龙 - 1301（CF₃Br）在紫外线辐射下会产生溴自由基，这对大气中的臭氧层构成巨大威胁。必须采取必要措施来降解哈龙 - 1301的废气。本文采用B3LYP/6 - 311G++(d,p)水平的密度泛函（DFT）理论，研究哈龙 - 1301在外部电场中的解离特性和光谱，包括键长、总能量、最高占据分子轨道 - 最低未占据分子轨道（HOMO - LUMO）能隙、红外光谱和解离势能面（PES）。所得结果表明，沿着分子轴Z（C—Br键方向）将外部电场从0逐渐增加到0.03原子单位（a.u.）时，总能量降低，而偶极矩先减小后增大。随着电场增强，HOMO - LUMO能隙增大，C—Br键长增加而C—F键长减小。还研究了外部电场中分子红外光谱振动频率和强度的变化。进一步研究表明，随着外部电场从0增加到0.03 a.u.，沿C—Br键的解离PES变为非束缚态，解离势垒消失。0.03 a.u.的外部电场足以诱导CF₃Br发生C—Br键断裂而降解。这些结果为通过外部电场降解哈龙提供了重要参考。
