1. Vacuum ultraviolet photodynamics of the methyl peroxy radical studied by double imaging photoelectron photoion coincidences.
- Author
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Tang, Xiaofeng, Gu, Xuejun, Lin, Xiaoxiao, Zhang, Weijun, Garcia, Gustavo A., Fittschen, Christa, Loison, Jean-Christophe, Voronova, Krisztina, Sztáray, Bálint, and Nahon, Laurent
- Subjects
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METHYL radicals , *PEROXY radicals , *PHOTOIONIZATION , *IONIZATION energy , *VACUUM , *PHOTOELECTRON spectra , *PHOTOELECTRONS - Abstract
The vacuum ultraviolet photoionization of the methyl peroxy radical, CH3O2, and unimolecular dissociation of internal energy selected CH3O2+ cations were investigated in the 9.7–12.0 eV energy range by synchrotron-based double imaging photoelectron photoion coincidence. A microwave discharge flow tube was employed to produce CH3O2 via the reaction of methyl radicals (CH3) with oxygen gas. After identifying and separating the different sources of CH3+ from photoionization of CH3 or dissociative photoionization of CH3O2, the high resolution slow photoelectron spectrum (SPES) of CH3O2 was obtained, exhibiting two broad bands superimposed with a complex vibrational structure. The first band of the SPES is attributed to the X3A″ and a1A′ overlapped electronic states of CH3O2+ and the second is assigned to the b1A′ electronic state with the help of theoretical calculations. The adiabatic ionization energy of CH3O2 is derived as 10.215 ± 0.015 eV, in good agreement with high-accuracy theoretical data from the literature. The vertical ionization energy of the b1A′ electronic state is measured to be 11.5 eV and this state fully dissociates into CH3+ and O2 fragments. The 0 K adiabatic appearance energy (AE0K) of the CH3+ fragment ion is determined to be 11.15 ± 0.02 eV. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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