Investigation of the complete valence shell of formic acid by electron momentum spectroscopy and Green's function methods

An (e,2e) coincidence study of formic acid monomer and dimer

“…Our (e,2e) MO binding energies are in excellent agreement with the previous experimental results [2,3,6]. Our SAOP/pVQZ and OVGF/TZVP calculations also…”

“…give binding energies in very good accord with the experiment, as do the ADC(3)/TZ results of Bharathi et al [6]. Note that only the ADC(3) binding energies for the major ionisation lines (poles) are listed here.…”

“…2. Table 3 summarises the present orbital assignments and experimental and theoretical binding energies, along with previous results [2,3,6], for the formic acid monomer.…”

“…The valence electronic structures of formic acid monomer and dimer have been studied extensively by photoelectron spectroscopy (PES) [2][3][4][5] but electron collision studies are limited. A previous EMS study by Bharathi et al [6] was conducted at room temperature where formic acid vapour contains considerable dimer concentration [7]. Unfortunately, these authors analysed their measured binding energy spectra only in terms of the monomer.…”

Concerted Double Hydrogen-Bond Breaking by Intermolecular Coulombic Decay in the Formic Acid Dimer

“…This corresponds to single ionization of both molecules within the dimer and is thus attributed to the ICD final state. Previous studies of the inner-valence ionization spectra of FA molecule − have shown that the carbon 2s (C 2s) type states contribute mainly to the ionization-energy region of about 20–28 eV, while the ionization bands above 28 eV are mostly built on oxygen 2s (O2s) type states, i.e., the 5a′ and 4a′ orbitals. Hence, these states are energetically accessible for initiating the ICD process in FAD.…”