kinetic-energy release distributions from chlorobenzene and related molecules in electron transfer experiments

Sarvesh Kumar; Pedro J. S. Pereira; Gustavo García; Paulo Limão-Vieira

doi:10.1140/epjd/s10053-021-00307-0

2024 Impact factor 1.5

Atomic, Molecular, Optical and Plasma Physics

Molecular collisions, photoionization and dynamics: honouring Professor Vincent McKoy

Eur. Phys. J. D (2021) 75: 294
https://doi.org/10.1140/epjd/s10053-021-00307-0

Regular Article – Atomic and Molecular Collisions

${Cl}^{-}$ $\hbox {Cl}^{-}$ kinetic-energy release distributions from chlorobenzene and related molecules in electron transfer experiments

Sarvesh Kumar¹, Pedro J. S. Pereira¹^,2, Gustavo García³ and Paulo Limão-Vieira¹^d

¹ Atomic and Molecular Collisions Laboratory, Department of Physics, CEFITEC, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal
² Department of Mathematics, Instituto Superior de Engenharia de Lisboa, 1959-007, Lisboa, Portugal
³ Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, 28006, Madrid, Spain

^d plimaovieira@fct.unl.pt

Received: 16 September 2021
Accepted: 8 November 2021
Published online: 22 November 2021

Abstract

We report a novel and comprehensive analysis of the chlorine anion ( ${Cl}^{-})$ $\hbox {Cl}^{-})$ kinetic energy release distributions (KERDs) from electron transfer experiments at 12, 40 and 118 eV collision energies in the centre-of-mass frame. These distributions have been obtained from the shape and width of ${Cl}^{-}$ $\hbox {Cl}^{-}$ time-of-flight mass spectra from collisions of neutral potassium (K) atoms with a set of selected neutral chlorinated compounds, viz. $C_{6} H_{5} Cl$ $\hbox {C}_{{6}}\hbox {H}_{{5}}\hbox {Cl}$ , $C_{6} D_{5} Cl$ $\hbox {C}_{{6}}\hbox {D}_{{5}}\hbox {Cl}$ , $C_{6} H_{11} Cl$ $\hbox {C}_{{6}}\hbox {H}_{{11}}\hbox {Cl}$ and $C_{6} {Cl}_{6}$ $\hbox {C}_{{6}}\hbox {Cl}_{{6}}$ . The reactions producing bond breaking of the temporary negative ions formed with an excess of internal energy in such collisions, are a result of intramolecular energy redistribution through the different available degrees of freedom due to statistical degradation via vibrational excitation and partly due to direct transformation into translational energy of the fragment anions. The ${Cl}^{-}$ $\hbox {Cl}^{-}$ low-energy kinetic energy release, $ε_{d}$ $\upvarepsilon _{\mathrm{d}}$ , has been fitted with a statistical function and the role of the different available resonances in the collision dynamics has been discussed, allowing therefore to obtain relevant information on the electronic structure involved in negative ion formation. From ${Cl}^{-}$ $\hbox {Cl}^{-}$ kinetic-energy release maxima as a function of the collision energy, $C_{6} {Cl}_{6}$ $\hbox {C}_{{6}}\hbox {Cl}_{{6}}$ shows the lowest values which have been attributed to the strong competition with the parent anion formation. In contrast, $C_{6} H_{11} Cl$ $\hbox {C}_{{6}}\hbox {H}_{{11}}\hbox {Cl}$ shows the highest values which result from this molecular system having no $π$ $\uppi$ delocalized electrons over the ring, and the electronic state spectroscopy is mostly dictated by relevant $σ$ $\upsigma$ * antibonding character along the C–Cl coordinate.