Non-covalent anion structures in dissociative electron attachment to some brominated biphenyls

0552253 - ÚFCH JH 2022 RIV US eng J - Journal Article
Asfandiarov, N. L. - Muftakhov, M. V. - Pshenichnyuk, S. A. - Rakhmeev, R. G. - Safronov, A. M. - Markova, A. V. - Vorob'ev, A. S. - Luxford, Thomas Frederick Murray - Kočišek, Jaroslav - Fedor, Juraj
Non-covalent anion structures in dissociative electron attachment to some brominated biphenyls.
Journal of Chemical Physics. Roč. 155, č. 24 (2021), č. článku 244302. ISSN 0021-9606. E-ISSN 1089-7690
R&D Projects: GA ČR(CZ) GA20-11460S; GA ČR(CZ) GA19-01159S
Institutional support: RVO:61388955
Keywords : Electrons * Mass spectrometers * Molecular physics
OECD category: Physical chemistry
Impact factor: 4.304, year: 2021
Method of publishing: Open access with time embargo

The present work combines experiment and theory to reveal the behavior of bromo-substituted-biphenyls after an electron attachment. We experimentally determine anion lifetimes using an electron attachment-magnetic sector mass spectrometer instrument. Branching ratios of dissociative electron attachment fragments on longer timescales are determined using the electron attachment-quadrupole mass spectrometer instrument. In all cases, fragmentation is low: Only the Br- and [M-Br]- ions are detected, and [M-H]- is observed only in the case of 4-Br-biphenyl and parent anion lifetimes as long as 165 μs are observed. Such lifetimes are contradictory to the dissociation rates of 2- and 4-bromobiphenyl, as measured by the pulse radiolysis method to be 3.2 × 1010 and >5 × 1010 s-1, respectively. The discrepancy is plausibly explained by our calculation of the potential energy surface of the dissociating anion. Isolated in vacuum, the bromide anion can orbit the polarized aromatic radical at a long distance. A series of local minima on the potential energy surface allows for a roaming mechanism prolonging the detection time of such weakly bound complex anions. The present results illuminate the behavior recently observed in a series of bromo-substituted compounds of biological as well as technological relevance.
Permanent Link: http://hdl.handle.net/11104/0327382