Electron impact ionization of furanose alcohols

Abstract

Electron impact ionization of the gas phase 3-furanol, tetrahydro (3-hydroxytetrahydrofuran, 3HTHF) and 2-furanmethanol, tetrahydro (alpha-tetrahydrofurfuryl alcohol, THFA) molecules has been studied both experimentally and theoretically. The electron induced positive ion formation has been investigated experimentally using a crossed electron/neutral beams technique in combination with a quadrupole mass spectrometry. The mass spectra of both molecules have been determined at the incident electron energy of 70 eV. The ionization efficiency curves for each parent cation and a number of fragment cations have been measured near the threshold, and the corresponding appearance energies have been derived using an iterative fitting procedure based on the Wannier threshold law, taking into account the incident electron energy resolution. The appearance energies of the parent cations were experimentally determined to be (9.620+/-0.058) eV for (C(4)H(8)O(2)(+)/3HTHF) and (9.43+/-0.12) eV for (C(5)H(10)O(2)(+)/THFA), which are in a good agreement with G3MP2 calculated results: 9.480 and 9.419 eV, respectively. The most abundant cations in the mass spectra were determined to be 57 amu for 3HTHF and 71 amu for THFA, with the corresponding experimentally determined appearance energies of (10.22+/-0.10) eV and (9.574+/-0.062) eV, respectively. With the help of the energies calculated at B3LYP and G3MP2 levels of theory, the possible fragmentation patterns were discussed.

Dynamical (e,2e) studies of tetrahydrofurfuryl alcohol

“…The present measured results are also in good agreement with the appearance energy measured for the THFA parent cation of 9.43 ± 0.12 eV (Ref. 48) and with previous photoelectron spectroscopy measurements. 45 The calculated momentum density probability distribution for the HOMO of THFA is presented in Figure 3.…”

Electron impact ionization of 1-butanol: II. Total ionization cross sections and appearance energies

“…Note that the above procedure is identical to that used in our recent work [54]. If we were to use equation 1, instead of equation 2, for the experimental data fitting, then the resultant fits give slightly higher values of the appearance energy, as shown in ref [69]. The appearance energy of argon (15.759 eV) [66] was used to calibrate the energy scale.…”

Intermediate-energy differential and integral cross sections for vibrational excitation in α-tetrahydrofurfuryl alcohol

“…However, significantly less experimental and theoretical effort has been devoted to THFA compared to THF. 5,10,13 The scattering data for THFA that is presently available in the literature (electron, positron, and photon) includes some independent atom method (IAM) elastic cross sections and binary-encounter Bethe (BEB) total ionisation cross sections, 14 a total cross section (TCS) measurement from Możejko et al, 15 some elastic DCS data 16 at intermediate to high energies, a dissociative ionisation study from Milosavljević et al, 17 and some dynamical (e,2e) investigations from Bellm et al 18 and Jones et al 19 More recently, a detailed study into electronic-state electron impact excitation (20-50 eV) in THFA has been advanced by Duque et al 12 and Chiari et al 20 We note that those latest investigations 12,20 also included IAM with screened additivity rule (SCAR) correction computations for elastic DCS and ICS and the TCS in THFA. From a positron perspective, we only know of the TCS measurement from Zecca et al 21 Photoionisation cross sections are also available, 11,22 as are photoabsorption cross sections from the very recent measurement of Limão-Vieira et al 11 That latter paper also contains a set of comprehensive electronic-structure calculations, which showed that of the six FIG.…”