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利用同步辐射真空紫外光电离结合飞行时间质谱对五氟乙烷(CHF2CF3)进行了光电离光解离的研究,测定了CHF2CF3的电离势及该分子主要碎片离子的出现势.结果表明:CHF2CF3的绝热电离势为(12.25±0.10)eV,主要碎片离子有CF2CF3+、CHFCF3+、CF2CF2+、CF3+、CHF2+、CHF+和CF+,其出现势分别为(13.93±0.10)eV,(15.25±0.10)eV,(15.12±0.10)eV,(13.30±0.05)eV,(13.05±0.08)eV,(19.17±0.10)eV和(19.56±0.15)eV.另外,用从头算分子轨道理论计算了解离电离过程中所有碎片的总能量,并给出了电子态及对称性.根据实验结果和理论计算,分析了可能的解离通道,并得到了分子及母体离子的键解离能等重要的热力学数据.
The photoionization of pentafluoroethane (CHF2CF3) was studied by synchrotron radiation vacuum ultraviolet photoionization combined with time-of-flight mass spectrometry, and the ionization potential of CHF2CF3 and the appearance potential of the major fragment ions of CHF2CF3 were determined. The adiabatic ionization potential was (12.25 ± 0.10) eV and the main fragment ions were CF2CF3 +, CHFCF3 +, CF2CF2 +, CF3 +, CHF2 +, CHF + and CF +. The appearance potentials were (13.93 ± 0.10) eV, (15.25 ± 0.10) ± 0.10) eV, (13.30 ± 0.05) eV, (13.05 ± 0.08) eV, (19.17 ± 0.10) eV, and (19.56 ± 0.15) eV respectively. In addition, all fragments in the ionization process were calculated using ab initio molecular orbital theory Total energy, and gives the electronic states and symmetries.According to the experimental results and theoretical calculations, the possible dissociation channels are analyzed and the important thermodynamic data such as the bond dissociation energies of the molecules and parent ions are obtained.