Singlet and triplet excitations in C5F10O induced by electrons and photons: Spectroscopy and dynamics.

Authors

Tomáš Ovad, Marin Sapunar, Zdeněk Mašín, Nykola C Jones, Søren Vrønning Hoffmann, Miloš Ranković, Pamir Nag, Juraj Fedor, Petr Slavíček

Published in

The Journal of chemical physics. Volume 165. Issue 16. Oct 28, 2026.

Abstract

C5F10O [heptafluoroisopropyl(trifluoromethyl)ketone] has emerged as a promising alternative to sulfur hexafluoride for the use in gas-insulated switchgears. Despite its technological relevance, its interactions with low-energy electrons remain largely unexplored. Electron impact can populate both singlet and triplet electronically excited states, potentially initiating dissociation pathways that yield toxic or technologically undesirable products. Here, we combine vacuum-ultraviolet (VUV) absorption spectroscopy, electron energy loss spectroscopy (EELS), and theoretical modeling to characterize the electronically excited states of C5F10O and the dynamics initiated by these excitations. We report the first VUV absorption spectrum of C5F10O and directly compare it to EELS recorded at multiple scattering angles and residual energies. The spectra are compared with high-level ab initio calculations. To obtain the inelastic electron scattering cross sections, we use our implementation of the Born approximation coupled with the algebraic diagrammatic construction of the second order method. An ad hoc extension of this approach is introduced to account for the exchange-mediated spin-forbidden transitions in the spectra of backscattered electrons. Finally, nonadiabatic molecular dynamics coupled with time-dependent density functional theory is used to identify reaction channels initiated in different singlet and triplet excited states. Overall, we provide a state-resolved framework to study electronic excitation and subsequent reactivity, with implications for plasma modeling and the design of next-generation high-voltage insulation media.

PMID:
42913406
Bibliographic data and abstract were imported from PubMed on 24 Oct 2026.

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