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Observation and assignment of the first photoelectron band of the CH3CO (X(2)A) radical

Zamanpour, M.H.N., Bahkshandeh, A., Ghaffarzadeh, S. and Dyke, J.M. (2008) Observation and assignment of the first photoelectron band of the CH3CO (X(2)A) radical Journal of Electron Spectroscopy and Related Phenomena, 162, (3), pp. 122-126. (doi:10.1016/j.elspec.2007.10.002).

Record type: Article


HeI photoelectron spectra have been recorded for the reaction of fluorine atoms with acetaldehyde at different reaction times. A structured band associated with a short-lived primary reaction product was recorded at a reactant mixing distance of 6 mm above the photon beam. The vertical ionization energy was measured as (8.39 ± 0.05 eV), and regularly spaced vibrational structure was observed in this band with an average vibrational separation of (1605 ± 30 cm?1). The band was assigned to ionization of the CH3CO (X2A) radical on the basis of first vertical ionization energies computed for the two possible primary products, CH3CO and CH2CHO, using ab-initio calculations. The calculations carried out on CH3CO (X2A), and its singlet ground cationic state, revealed that the observed vibrational structure can be assigned to excitation of the Csingle bondO stretching mode in the ion. The measured adiabatic ionization energy, 7.21 ± 0.05 eV, is higher than the value expected (6.94 ± 0.03 eV) from evidence in the literature and calculated values in this work. This difference is assigned to poor Franck–Condon factors in the region of the band onset which means that the true adiabatic ionization energy was not observed.

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Published date: March 2008
Keywords: spectra, heat, spectroscopy, laser-induced fluorescence, vertical ionization energy, photoelectron spectra, adiabatic ionization, energy, g1/g2 computational calculations


Local EPrints ID: 54512
PURE UUID: f5c41c88-00ff-41d8-a06e-50e81dc6e016
ORCID for J.M. Dyke: ORCID iD

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Date deposited: 22 Aug 2008
Last modified: 17 Jul 2017 14:35

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Author: M.H.N. Zamanpour
Author: A. Bahkshandeh
Author: S. Ghaffarzadeh
Author: J.M. Dyke ORCID iD

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