三氯一氟甲烷分子在辐射场中的光谱性质与解离特性研究

Spectrum and dissociation properties of fluoro trichloro methane molecule in radiational field

采用B3LYP/6-311++g(3df,3pd)方法和基组对氟利昂物质CFC-11 (CFCl_3)分子进行了一系列的理论研究.包括了该分子的基态结构、电偶极矩、总能量、最高占据分子轨道能级E_H和最低未占据分子轨道能级E_L、能隙、红外与拉曼光谱性质、C-F键解离,并探讨电场对该分子的影响.结果表明:基态结构优化后的理论计算值和实验值的最大误差低于2%,C-F键受电场强度的增大而被拉长,能隙E_g随E_H和E_L的变化出现先增大后减小;电场影响着CFC-11分子的红外与拉曼光谱吸收强度,红外与拉曼光谱随着电场变化出现红移或蓝移现象.电场可作为一种辅助手段对其重叠或准重叠谱线进行分离.势阱深度随反向电场逐渐增大而减小,直至消失,使得C-F键的束缚能力逐渐减弱.本文有望为实现CFC-11分子最终发生解离而降解提供一种可行有效的调控手段.

The ozone layer in the stratosphere of the earth’s atmosphere, which can be destroyed by CFC-11 molecule, plays a crucial role in human survival because it can absorb most of the harmful radiation from the sun and effectively protect the earth’s biology. Therefore, it is of evident significance to investigate the properties of CFC-11 molecule. By Motivated by this and the adoption of B3 LYP complex function at a level of6-311++g(3 df, 3 pd) basis set, we carry out a series of theoretical studies of the Freon material CFC-11(CFC13)molecules, including the studies of the equilibrium structure, electric dipole moment, total energy, the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) level, energy gap infrared and Raman spectrum, C—F dissociation characteristics of CFC-11 molecule, and the effect of the applied electric field on CFC-11 molecule as well. The results show that the maximum error between the theoretical calculation value and the experimental value is less than 2% for an optimized ground state structure;the C—F bond length and C—Cl bond length extend with the increase of electric field intensity, but the degree of change of C—F bond length is much stronger than that of C—Cl;the HOMO energy level and total energy go up and then come down as the external field rises, while the LUMO energy level goes up as the field increases. The energy gap E_g first increases and then decreases with the variation of E_H and E_L. The dipole moment without electric field is a minimum value, and the external electric field leads the molecular polarity to increase and the molecular activity to strengthen. The electric field influences the absorption intensity of infrared and Raman spectrum. The infrared and Raman spectrum move toward the long wave under the action of positive electric field, while they move toward the short wave under the action of negative electric field. The red-or blue-shift of infrared and Raman spectrum occur with the change of electric field. The electric field can be adopted as an auxiliary means to separate the overlapping or quasi-overlapping spectral lines. The potential well depth decreases with the increase of the reverse electric field until it vanishes, which causes the bound state ability of C—F bond of CFC-11 molecule to gradually degrade. This paper is expected to provide a feasible and effective tunable means for the final dissociation and degradation of CFC-11 molecules.