Agradecimentos: This work has been supported by Coordenação de Aperfeiçoamento de Pessoal de Ni'vel Superior (CAPES/MEC, Brazil), Conselho Nacional de Desenvolvimento Cienti'fico e Tecnológico (CNPq/MCT, Brazil), Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB, Brazil), and Laboratório Nacional de Luz Si'ncrotron (LNLS, Brazil) Ver menos

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 (H2O+) Ver menos