Observation of rovibrationally coupled bi-modality and speed-dependent orientation in DEA dynamics of OCS: reveals partial correlations among point group symmetries

Dissociative electron attachment (DEA) to gas-phase carbonyl sulfide (OCS) has been studied diligently using the time-of-flight (TOF) based state-of-the-art velocity map imaging (VMI) technique. Three well-resolved DEA resonances are observed at 5.0, 6.5 and 10.0 eV incident electron energies along with a weak structure at 8.0 eV. The velocity slice images (VSI), Kinetic energy (KE) and angular distributions (AD) for the fragmented sulfur anions are obtained using the wedge slicing technique. The KE distributions for the sulfur nascent fragments reveal bi-modality with rovibrational signatures. The ADs substantiate speed-dependent angular anisotropy demand the existence of partial correlations among three different point group symmetries, confirmed through an in-plane bending mode of vibration with the axial recoil breakdown. Theoretical calculations using R-matrix and density functional approaches strongly support the experimental observations.