Formation of Hydroxyl Anion via a 2-Particle 1-Hole Feshbach Resonance in DEA to 2-Propanol: A Joint Experimental and Theoretical Study

TL;DR

This study combines experimental measurements and advanced theoretical calculations to elucidate the formation of hydroxyl anions via a specific Feshbach resonance during dissociative electron attachment to 2-propanol, revealing the role of multi-electron resonances in bond cleavage.

Contribution

It provides the first combined experimental and theoretical analysis of a 2-particle-1-hole Feshbach resonance in DEA to 2-propanol, elucidating the resonance's role in hydroxyl group dissociation.

Findings

Resonance centered at 8.2 eV causes OH- formation.

Core-excited anion states facilitate hydroxyl cleavage.

Long-lived antibonding sigma states contribute to OH- production.

Abstract

Absolute cross sections for the formation of OH- from 2-propanol (CH3CH(OH)CH3) via dissociative electron attachment (DEA) are reported in the incident electron energy range of 3.5-13 eV. Four fragment anions are observed: OH-, C2H2O-, C2H4O-, and C3H7O-. The OH- yield exhibits a pronounced resonance centered at 8.2 eV together with a broader structure extending over the 8-10 eV region. Equation-of-Motion Coupled-Cluster (electron attached) calculations with Singles and Doubles combined with a Complex Absorbing Potential (CAP/EOM-EA-CCSD) assign this feature to a two-particle-one-hole (2p-1h) core-excited Feshbach resonance. Potential energy curves along the C-OH dissociation coordinate reveal that core-excited anion states in this energy range promote efficient cleavage of the hydroxyl group. Analysis of Dyson orbitals and resonance widths demonstrates that only states with repulsive antibonding sigma(C-OH) character and sufficiently long lifetimes contribute significantly to the observed OH- production. These results provide fundamental insight into the DEA dynamics of secondary alcohols and highlight the role of multi-electron-attached resonances in site-specific bond rupture induced by low-energy electrons.