Study on the atmospheric photochemical reaction of CF3 radicals using ultraviolet photoelectron and photoionization mass spectrometer

A study of the atmospheric photochemical reaction of CF₃ radical with CO and O₂ was performed by using a homemade ultraviolet photoelectron spectrometer-photoionization mass spectrometer (PES-PIMS). The electronic structures and mechanism of ionization and dissociation of CF₃OC(O)OOC(O)-OCF₃ were investigated. It was indicated that the two bands on the photoelectron spectrum of CF₃OC(O)OOC(O)OCF₃ are the result of ionization of an electron from a lone pair of oxygen and a fluorine lone pair of CF₃ group. The outermost electrons reside in the oxygen lone pair. The experimental and theoretical first vertical ionization energy is 13.21 and 13.178 eV, respectively, with the PES and OVGF method. They are in good agreement. The photo ionization and dissociation processes were discussed with the help of theoretical calculations and PES-PIMS experiment. After ionization, the parent ions prefer the dissociation of the C—O bond and giving the fragments CF₃OCO⁺ and CF₃⁺. It demonstrated that the ultraviolet photoelectron and photoionization mass spectrometer could be applied widely in the study of atmospheric photochemical reaction. Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-205), Hundred Talents Fund, 973 Program of Ministry of Science and Technology of China (Grant No. 2006CB403701) and the National Natural Science Foundation of China (Grant Nos. 20577052, 20673123)