Structural rearrangements and fragmentation pathways induced by a low-energy electron attachment to ethyl acetate

The phenomenon of dissociative electron attachment to ethyl acetate is investigated within the 1 to 13 eV energy region. The recorded yields of various fragment anions within the above-mentioned energy range reveal a diverse array of products with six different mass numbers. Examples include (${M-\mathrm{H})}^{-}$, ${\mathrm{CH}}_3{}^{-}$, ${\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{O}}^{-}$, ${\mathrm{CH}}_3{\mathrm{CO}}^{-}$, ${\mathrm{CH}}_2{\mathrm{CHO}}^{-}$, and ${\mathrm{CH}}_3{\mathrm{COO}}^{-}$, formed through the fracture of single bonds. Interestingly, the generation of other fragments, such as ${\mathrm{HCCO}}^{-}$, suggests a more intricate structural rearrangement of the nuclei, adding a layer of complexity to the observed dissociation dynamics.

Figure 1

Ion-yield curve of (${M-\mathrm{H})}^{-}$ ions produced due to DEA to ethyl acetate in the energy range of 1–13 eV. A single resonant peak at 2.7 eV is observed.

Figure 2

The VUV photoabsorption spectrum of ethyl acetate was extracted from a previous report [29]. This spectrum reveals the presence of four absorption bands within the 5–10 eV energy region. The ion yield of ${\mathrm{CH}}_3{}^{-}$ ions produced due to DEA to ethyl acetate in the energy range of 1–13 eV is also presented at the bottom. The blue dots represent the experimental data points, and the black solid curve indicates the cumulative fitted curve with four Gaussian functions attributed to four resonant bands (illustrated in red, blue, yellow, and pink). One exponential function is also shown to incorporate the contribution of the IP dissociation process (solid green curve). The fitting suggests that the structure present in the 5–12 eV range is a combination of four resonant states with energies at 5.7, 7.3, 8.5, and 10.1 eV.

Figure 3

The ion yield of ${\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{O}}^{-}$ ions produced due to DEA to ethyl acetate in the energy range of 1 to 13 eV. The blue dots represent the experimental data points, and the black solid line represents the cumulative fit of the ion yield with three Gaussian functions (illustrated in sky blue, dark blue, and pink). The fitting suggests that the structure present in the 3.0 eV region is due to the contribution of a shape resonance, whereas the 6–12 eV region is a combination of two core-excited Feshbach resonances peaking at 7.3 and 9.9 eV.

Figure 4

The ion yield of ${\mathrm{CH}}_3{\mathrm{CO}}^{-}$ ions produced due to DEA to ethyl acetate in the energy range of 1 to 13 eV. The blue dots represent the experimental data points, and the black solid line represents the cumulative fit of the ion yield with three Gaussian functions (illustrated in blue, yellow, and pink). The fitting suggests that the structure present in the 6–12 eV region is a combination of three core-excited Feshbach resonances peaking at 7.3, 8.2, and 10.1 eV.

Figure 5

The ion yield of ${\mathrm{CH}}_3{\mathrm{COO}}^{-}$ ions produced due to DEA to ethyl acetate in the energy range of 1 to 13 eV. The blue dots represent the experimental data points, and the black solid line represents the cumulative fit of the ion yield with three Gaussian functions (illustrated in sky blue, yellow, and pink). The fitting suggests that the structure present in the 3 eV region is due to the contribution of a shape resonance, whereas the 6–12 eV region is a combination of two core-excited Feshbach resonances peaking at 8.9 and 10.2 eV.

Figure 6

The ion yield of ${\mathrm{HCCO}}^{-}$ ions produced due to DEA to ethyl acetate in the energy range of 1 to 13 eV. The blue dots represent the experimental data points, and the black solid line represents the cumulative fit of the ion yield with three Gaussian functions (illustrated in sky blue, dark blue, and pink). The fitting suggests that the structure present in the 3.3 eV region is due to the contribution of a shape resonance, whereas the 6–12 eV region is a combination of two core-excited Feshbach resonances peaking at 7 and 9.7 eV.

Figure 7

Suggested fragmentation pathways of ethyl acetate producing ${\mathrm{HCCO}}^{-}$ during the DEA process. Structural rearrangements in the molecular anion must occur. The two fragmentation channels on the left show the pathways when the C–O dissociation occurs near the keto site of the molecule, whereas the right pathway represents when the C–O dissociation occurs near the ethyl group.