title: Theoretical-experimental study of formic acid photofragmentation in the valence region.
abstract: Photoionization and photofragmentation studies of formic acid (HCOOH) are performed for the valence shell electron ionization process. The total and partial ion yield of gaseous HCOOH were collected as a function of photon energy in the ultraviolet region, between 11.12 and 19.57 eV. Measurements of the total and partial ion yield of gaseous formic acid molecule are performed with a time-of-flight mass spectrometer at the Synchrotron Light Brazilian Laboratory. Density functional theory and time dependent density functional theory are employed to calculate the ground and excited electronic state energies of neutral and ionic formic acid as well as their fragments and normal vibration modes. The ionization potential energies, the stability of electronic excited states of HCOOH(+), and the energies of opening fragmentation channels are estimated from theoretical-experimental analysis. Additionally, the main formic acid photofragmentation pathways by exposition of photons within that energy range are determined experimentally. These produced ions primarily have the following mass/charge ratios: 46 (HCOOH(+)), 45 (COOH(+)), 29 (HCO(+)), and 18 (H(2)O(+)).
authors.affiliation: Instituto de Física, Universidade Federal da Bahia, 40210-340 Salvador, BA, Brazil.
authors.forename: Manuela S
authors.initials: MS
authors.lastname: Arruda
authors.forename: Ricardo R T
authors.initials: RR
authors.lastname: Marinho
authors.forename: Angelo M
authors.initials: AM
authors.lastname: Maniero
authors.forename: Maria Suely P
authors.initials: MS
authors.lastname: Mundin
authors.forename: Alexandra
authors.initials: A
authors.lastname: Mocellin
authors.forename: Sergio
authors.initials: S
authors.lastname: Pilling
authors.forename: Arnaldo N
authors.initials: AN
authors.lastname: de Brito
authors.forename: Frederico V
authors.initials: FV
authors.lastname: Prudente
mesh_terms: D004583:Electrons; D005561:Formates / Q000737:chemistry*; D055668:Photochemical Processes; D011789:Quantum Theory; D014732:Vibration
chemical_list: D005561:Formates; C030544:formic acid