We report a combined experimental and theoretical investigation of electron scattering from nitrous oxide (N2O). Experimental two-dimensional electron energy loss spectra (EELS) provide information about vibrational states of a molecule and about potential energy surfaces of anionic resonances. This study reports the EELS measured at 2.5–2.6 eV incident energy. The calculations using complex-valued extensions of equation-of-motion coupled-cluster theory (based on the non-Hermitian quantum mechanics) facilitate the assignment of all major EELS features. Our simulations identified two broad and partially overlapping resonances—one of π* and another of σ* character—located at ∼2.8 and 2.3 eV vertically at the equilibrium geometry of the neutral. Due to the Renner–Teller effect, the π* resonance splits upon bending. The upper state, 2Π, remains linear. The lower state mixes with the σ* configuration, giving rise to the 2A′ resonance, which becomes strongly stabilized at bent geometries (αNNO = 134°), resulting in very low adiabatic electron attachment energy. The calculations estimate the electron affinity of N2O to be −0.140 eV. The 2A′ state is predissociative, with the barrier for the N–O bond dissociation of 0.183 eV. The measured EELS feature sharp vibrational structures at low energy losses, followed by a linear (in logarithmic scale) tail extending to the maximum energy loss. The simulations attribute the sharp features at the low energy loss to the non-resonant excitations and contributions from the cold 2Π resonance. The tail is attributed to the vibrationally hot 2A′ state, and its slope is determined by the excess energy available in this state.
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Electron-induced vibrational excitation and dissociative electron attachment in methyl formate
We probe the low-energy electron collisions with methyl formate HCOOCH 3 , focusing on its resonant states. Experimentally, we (i) use two-dimensional electron energy loss spectroscopy to gain information about the vibrational excitation and (ii) report the absolute dissociative electron attachment cross sections. The electron scattering spectra reveal both the threshold effects due to the long-range electron–molecule interaction and a pronounced π* resonance centered around 2.1 eV. This resonance gives rise to dissociative electron attachment into three different anionic channels, the strongest one being the production of the formate anion. Theoretically, we characterize this resonant state using the complex absorbing potential approach combined with multistate multireference perturbation theory, which predicts its position and width in excellent agreement with the experiment.
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- Award ID(s):
- 1665276
- PAR ID:
- 10202564
- Date Published:
- Journal Name:
- Physical Chemistry Chemical Physics
- Volume:
- 22
- Issue:
- 2
- ISSN:
- 1463-9076
- Page Range / eLocation ID:
- 518 to 524
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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