Low-energy electron-induced ion-pair dissociation to "Trilobite-resembling" long-range heavy Rydberg system

Abstract

We have studied electron-induced ion-pair dissociation dynamics of CO using the state-of-art velocity map imaging technique in combination with a time-of-flight-based two-field mass spectrometer. Extracting the characteristics for O$^-$/CO nascent atomic anionic fragments from the low energy (25 - 45 eV) electron-molecule scattering, first-time, we have directly detected the existence of S-wave resonated Trilobite resembling a novel molecular binding energy mechanism, as predicted by Greene \textit{et al.} \cite{greene2000creation}. The energy balance demands ion-pair dissociation (IPD) lie within a long-range (<1000 Bohr radius) heavy Rydberg system. Modified Van Brunt expression capturing the deflection of dipole-Born approximation is used to model the angular distributions (AD) for the anionic atomic fragments. The AD fits reveal that the final states are dominantly associated with $\Sigma$ symmetries and a minor contribution from $\Pi$ symmetric states that maps the three-dimensional unnatural oscillation of Born-Oppenheimer's potential.