Resonant low energy electron capture and fragmentation pathways of anisole.

Dissociative electron attachment (DEA) is a resonant process by which a low-energy electron attaches to a molecule, produces a transient negative ion, and then splits into a fragment negative ion and neutral conjugate(s). DEA helps to gain a better understanding of a molecule's dissociation dynamics and resonant state behavior. Anisole's simple structure yet relative reactivity compared with the non-substituted benzene makes it an important precursor for many practical compounds such as anethole -- a common flavoring agent. Previous DEA studies of anisole along with other asymmetric ethers are important for their application within low-pressure plasmas since these plasma systems contain an excess of secondary low-energy electrons [1]. Though these analyses have found extensive ion yields from compounds similar to anisole such as benzyl methyl ether, they are yet to find any significant fragment ion yields from anisole itself. A DEA study of anisole can also help expand the data base on the electron-induced cleavage of the stable benzene ring, which some previous studies have shown is possible, though each study provides different possible ion fragments that can be formed from the benzene ring. By using our instrumentation [2], we measured the ion yields of different negative ions produced from DEA to anisole at an incident electron energy range from ~0 to 14 eV. Three fragment anions with masses 15 au, 25 au, and 31 au are observed. The ion yields of masses 15 au and 31 au reflect the expected dissociation of the ether system that leaves the aromatic ring intact. However, the ion yield of mass 25 au indicates a cleavage of the benzene ring, which is relevant to several aromatic compounds that are present in physiological systems with excess secondary electrons. At the Conference, these results will be discussed in greater detail.

[1] C. Bulliard, M. Allan, and S. Grimme, Int. J. Mass Spec. 205 43-55 (2001)



[2] D. Chakraborty, L. Eckermann, I. Carmichael and S. Ptasinska, J. Chem. Phys. 153, 224306 (2020).