Valence and Inner Electronic Excitation, Ionization, and Fragmentation of Perfluoropropionic Acid

The photoexcitation, photoionization, and photofragmentation of gaseous CF₃CF₂C(O)OH were studied by means of synchrotron radiation in the valence and inner energy regions. Photofragmentation events were detected from 11.7 eV through formation of COH⁺, C₂F₄⁺, and the parent species M⁺. Because the vertical ionization potential has been reported at 11.94 eV, the starting energy used in this study, 11.7 eV, falls just inside of the tail of the ionization band in the photoelectron spectra. Information from the total ion yield spectra around the C 1s, O 1s, and F 1s ionization potentials allows the energies at which different resonance transitions take place in the molecule to be determined. These transitions have been assigned by comparison with the results of the analysis of similar compounds. In the inner energy region, both kinetic energy release (KER) values and the slope and shape of double coincidence islands obtained from photoelectron-photoion-photoion coincidence (PEPIPICO) spectra allow different photofragmentation mechanisms to be elucidated.