Observation of Resonant Tunneling from Molecular Shape into Vibronic Feshbach Resonances Followed by Mode-Specific Fragmentation

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Autori principali: Kundu, Narayan, Rana, Meenakshi, Ghosh, Aryya, Nandi, Dhananjay
Natura: Preprint
Pubblicazione: 2025
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author Kundu, Narayan
Rana, Meenakshi
Ghosh, Aryya
Nandi, Dhananjay
author_facet Kundu, Narayan
Rana, Meenakshi
Ghosh, Aryya
Nandi, Dhananjay
contents We present a kinematically complete study of dissociative electron attachment (DEA) in linear OCS molecules, focusing on how electrons resonantly attach and trigger dissociation. Near the Franck-Condon regime, DEA is dominated by molecular shape resonances, where transient OCS$^-$ states form with high vibrational amplitudes, spectroscopically evident as broad features in DEA cross-sections. As the electron beam energy increases from 5.5 to 6.0 eV, S$^-$ population shifts from lower to higher-energy highly dense bending vibrational states, reinforcing our findings on dipole-forbidden vibronic intensity borrowing. Our advanced potential energy curve calculations, employing the Equation-of-motion coupled cluster singles and doubles for electron attachment (EA-EOMCCSD) method, reveal that beyond the shape resonance, non-adiabatic resonant tunneling governs the avoided crossings, dynamically generating three mode-specific vibronic Feshbach resonances before complete dissociation into three distinct kinetic energy bands of S$^-$. Our theoretical results probe most of the experimental observations quantitatively and qualitatively. These insights deepen our fundamental understanding of resonance-mediated dissociation in electron-molecule resonant scattering, with broader implications for quantum mechanics, plasma physics, vibrational revival, astrochemistry, and radiation damage research.
format Preprint
id arxiv_https___arxiv_org_abs_2505_00532
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of Resonant Tunneling from Molecular Shape into Vibronic Feshbach Resonances Followed by Mode-Specific Fragmentation
Kundu, Narayan
Rana, Meenakshi
Ghosh, Aryya
Nandi, Dhananjay
Atomic and Molecular Clusters
Chemical Physics
Quantum Physics
We present a kinematically complete study of dissociative electron attachment (DEA) in linear OCS molecules, focusing on how electrons resonantly attach and trigger dissociation. Near the Franck-Condon regime, DEA is dominated by molecular shape resonances, where transient OCS$^-$ states form with high vibrational amplitudes, spectroscopically evident as broad features in DEA cross-sections. As the electron beam energy increases from 5.5 to 6.0 eV, S$^-$ population shifts from lower to higher-energy highly dense bending vibrational states, reinforcing our findings on dipole-forbidden vibronic intensity borrowing. Our advanced potential energy curve calculations, employing the Equation-of-motion coupled cluster singles and doubles for electron attachment (EA-EOMCCSD) method, reveal that beyond the shape resonance, non-adiabatic resonant tunneling governs the avoided crossings, dynamically generating three mode-specific vibronic Feshbach resonances before complete dissociation into three distinct kinetic energy bands of S$^-$. Our theoretical results probe most of the experimental observations quantitatively and qualitatively. These insights deepen our fundamental understanding of resonance-mediated dissociation in electron-molecule resonant scattering, with broader implications for quantum mechanics, plasma physics, vibrational revival, astrochemistry, and radiation damage research.
title Observation of Resonant Tunneling from Molecular Shape into Vibronic Feshbach Resonances Followed by Mode-Specific Fragmentation
topic Atomic and Molecular Clusters
Chemical Physics
Quantum Physics
url https://arxiv.org/abs/2505.00532