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

Abstract

The photoexcitation, photoionization and photofragmentation of gaseous CF 3 CF 2 C(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 + , C 2 F 4 + and the parent species M + . Since the vertical ionization potential has been reported at 11.94 eV, the starting energy used in this study, 11.7 eV, falls just inside the tale of the ionization band in the photoelectron spectra.The 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.

Angular Distribution of Ion Products in the Double Photoionization of Propylene Oxide

“…For this purpose we have used the PEPIPICO technique and the related data analysis procedure described in the previous section has been widely employed by our research group during the last 15 years studying the dissociative double photoionization of different simple molecules, as: (i) N 2 O, where we found a very strong anisotropy distribution for both ion pair products of the two dissociative channels leading to N + + NO + and O + + N2+ indicating that N 2 O molecules ionize when their axis is parallel to the light polarization vector, and the fragment ions are separating in a time shorter than the dication rotational period of about 10 −11 s (Alagia et al, 2007); (ii) CO 2 with the production of intermediates CO22+ dications having a lifetime of ~3.1 μs which form O + ions with a very high kinetic energy content able to explain their escape from the upper atmosphere of Mars (Alagia et al, 2010; Falcinelli et al, 2016a); and (iii) C 2 H 2 where a quite evident change in the anisotropy β parameter (see below) related to the symmetric CH + + CH + fragmentation reaction indicating that two microscopic mechanisms involving several electronic states of the intermediate C 2 H22+ molecular dication are operative (Alagia et al, 2012b). Recently others research groups using the same PEPIPICO technique performed interesting experiments studying the photodissociation of simple organic molecules, as alcohols (Bava et al, 2015), carboxylic acid (Arruda et al, 2016), and perfluoropropionic acid (Martínez et al, 2018).…”

Perfluoropropionic Acid-Driven Nucleation of Atmospheric Molecules under Ambient Conditions

“…It is also necessary to establish the sources of production of these elements. It is believed that they may have been produced by photodegradation of new refrigerants that replaced chlorofluorocarbons and photodegradation or thermodialysis of fluoropolymers. , Several quantum chemical investigations on PFPA were carried out covering different aspects of the molecule such as rotational and vibrational spectrum, degradation mechanisms, and interactions with water and amino acids in the last few years. − …”