Ab initio investigation of the autoionization process Ar*(4sP23,P3)+Hg→(Ar–Hg)++e−: Potential energy curves and autoionization widths, ionization cross sections, and electron energy spectra

Abstract

Multireference configuration interaction (MRCI) calculations have been performed for the Ar*(4s3P2,0) + Hg collision complex. Feshbach projection based on orbital occupancy defines the entrance channel resonance states and provides their potential energy curves as well as resonance-continuum coupling matrix elements, which are turned into an autoionization width function by Stieltjes imaging. Coupled cluster calculations with singles, doubles, and pertubative triples [CCSD(T)] give the exit channel potential of ArHg+. The Hg20+ core is treated by a scalar-relativistic effective core potential, reparametrized to reproduce experimental excitation and ionization energies. Spin-orbit interaction is included for the Ar* open 3p shell. The nuclear motion is treated within the local complex potential approximation. Ionization occurs for 85% (3P0) and 98% (3P2) of the symmetry allowed close collisions. Calculated ionization cross sections show good agreement with experimental data. The difference potential of the collision complex is remarkably flat down to internuclear separations of 8a0 and leads to very sharp peaks in theoretical electron energy spectra for single collision energies. After accounting for the experimental energy distribution and the resolution function of the spectrometer, a very satisfying agreement with experimental electron energy spectra is found, including subtle differences due to spin-orbit coupling. Theoretical input appears indispensable for an analysis of the measured data in terms of potential energy curves and autoionization width functions.

Effect of non-Maxwellian electron energy distribution functions on the simulation of an inductively coupled Ar–Hg discharge

“…If the gas temperature is T gas , then w = 8kT gas /(π M Hg ), where M Hg is the mass of the Hg atom. The rate of PI between excited Ar atoms and ground Hg atoms is set to 1.79 × 10 −15 m 3 s −1 , referring to [41]. Recombination between molecular Hg ion Hg + 2 and electrons is introduced as a loss mechanism of electrons.…”

Dissociative Ionization of Na2 via Repulsive Rydberg States: Elucidating Femtosecond Dynamics with Nanosecond Lasers

“…Superexcited states of molecules such as these Rydberg states are short-lived electronic resonances that play important roles in various molecular processes such as dissociative electron-ion recombination, [1][2][3] associative ionization, 4,5 and dissociative photoionization. 6,7 These resonances may be regarded as the electronic analog to transition states in molecular dynamics connecting reactants and products to each other.…”

“…Superexcited states of molecules such as these Rydberg states are short-lived electronic resonances that play important roles in various molecular processes such as dissociative electron−ion recombination, – associative ionization, , and dissociative photoionization. , These resonances may be regarded as the electronic analog to transition states in molecular dynamics connecting reactants and products to each other. , For example, collisions of two sufficiently excited atoms can carry them along suitable potential curves such that at sufficiently close internuclear distances their combined electronic energy is above that of the lowest molecular ion state. In that case, intramolecular electron−electron interactions can lead to associative ionization and the ejection of one of the electrons.…”