Structural rearrangements as relaxation pathway for molecular negative ions formed vibrational Feshbach resonance

• Published in: Physical chemistry chemical physics : PCCP 2020-07, Vol.22 (28), p.1615-16156
• Main Authors: Pshenichnyuk, Stanislav A, Asfandiarov, Nail L
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d0cp02647f

The low-energy (0-15 eV) resonance electron interaction with two organic acids, oxaloacetic and α-ketoglutaric, is studied under gas-phase conditions using dissociative electron attachment spectroscopy. The most unexpected observation is the long-lived (microseconds) molecular negative ions formed by thermal electron attachment via the vibrational Feshbach resonance mechanism in both compounds. Unlike oxaloacetic acid, for which only one slow (microseconds) dissociative decay is detected, as many as five metastable negative ions are observed for α-ketoglutaric acid. These results are analyzed using density functional theory calculations and estimations of electron affinity using the experimental electron detachment times. The results are of considerable interest for understanding the fundamental mechanisms responsible for the dynamics of highly excited negative ions and the transformation pathways of biologically relevant molecules stimulated by excess electron attachment. Thermal electron attachment to small linear molecules generates long-lived (microseconds) molecular negative ions with pseudo-cyclic structures by internal rotations.