Abstract
The single ionization and dissociation of ethanol molecules induced by low-energy electrons (E0 = 90 eV) are investigated using multiparticle coincident momentum spectroscopy. By detecting two outgoing electrons (e1 and e2) and one fragment ion in coincidence, we obtain the energy deposition (E0 − E1 − E2) during electron ionization of the molecule, i.e., the binding energy spectra, for production of the different ionic fragments C2H5OH+, C2H4OH+, COH+, and H3O+. These data allow us to study the ionization channels for different ionic products. In particular, we focus on H3O+ as a product of double hydrogen migration. It is found that this channel mainly originates from the ionization of outer-valance orbitals (3a″,10a′, 2a″, 9a′, 8a′, 1a″, and 7a′). Additionally, there are minor contributions from the inner-valence orbitals such as 6a′, 5a′, and 4a′. Quantum chemistry calculations show two fragmentation pathways: concerted and sequential processes for formation of H3O+.
Highlights
The experimental data for C2H5OH+ correspond to a single peak located at about 10.8 eV, which is consistent with the ionization energy of the highest occupied molecular orbital (HOMO) of ethanol [32]
This result indicates that the C2H5OH+ parent ion is formed through the HOMO ionization, i.e., the 3a′′ orbital of the trans conformer [32]
We determine the binding energy (BE) spectra correlated with different ionic fragments, i.e., and the parent ion the hydrogen
Summary
Particle beam and laser-induced ionization and fragmentation of molecules have attracted considerable interest for several decades [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]. H3O+ formation has been studied by Raalte and Harrison in an electron impact ionization experiment with deuterated ethanol. The two hydrogen migration directly follows single ionization of ethanol, while the sequential path. Further studies using the time of flight (TOF) spectra and the quantum chemical calculations confirmed that the sequential process is the dominant pathway for the formation of H3O+ in ethanol [25, 26]. We study the ionization and dissociation of ethanol irradiated by low-energy electrons using an
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