General treatment for stereo-dynamics of state-to-state chemi-ionization reactions

Abstract

The investigation of chemi-ionization processes provides unique information on how the reaction dynamics depend on the energy and structure of the transition state which relate to the symmetry, relative orientation of reagent/product valence electron orbitals, and selectivity of electronic rearrangements. Here we propose a theoretical approach to formulate the optical potential for Ne*(3 P 2,0) noble gas atom chemi-ionizations as prototype oxidation processes. We include the selective role of atomic alignment and of the electron transfer mechanism. The state-to-state reaction probability is evaluated and a unifying description of the main experimental findings is obtained. Further, we reproduce the results of recent and advanced molecular beam experiments with a state selected Ne* beam. The selective role of electronic rearrangements within the transition state, quantified through the use of suitable operative relations, could cast light on many other chemical processes more difficult to characterize.

Theoretical and Computational Analysis at a Quantum State Level of Autoionization Processes in Astrochemistry

“…( 11 ) below). This provided an internally consistent rationalization of most relevant experimental findings, characterized with different techniques in various laboratories, that includes total and partial ionization cross sections, BRs and PIES measurements [ 53 – 56 ]. The energy dependence of BRs between selected reaction channels must also relate with the PIES spectra for systems measured in our laboratory [ 5 , 39 , 40 ] as those reported in Fig.…”

“…The interaction components, formulated as summarized above and published in recent papers [ 45 , 53 ], permitted us to calculate within the semiclassical method outlined in Sect. 3 , the total ionization cross sections in a wide collision energy range for three investigated (where Ng = Ar, Kr and Xe) autoionization systems.…”

Chemi-Ionization Reactions and Basic Stereodynamical Effects in Collisions of Atom-Molecule Reagents

“…Accordingly, completely different exponential functions have been adopted for the two imaginary terms, formulated as suggested from the detailed study of atom–atom reactions. 6 , 7 …”

“…The total and partial (i.e., referred to each mechanism) ionization cross sections predicted by our method, and calculated within the semiclassical treatment, whose details can be found in refs ( 6 ) and ( 7 ), are shown in Figure 5 . The results show that the role of two mechanisms and their energy dependence are completely different for the two geometries here considered, since the combination of the intermolecular potential and the centrifugal barrier selectively modulates the range of intermolecular distances probed so exalting the different role of direct and indirect mechanisms.…”

Gas Phase TiO₂ Photosensitized Mineralization of some VOCs: Mechanistic Suggestions Through a Langmuir-Hinshelwood Kinetic Approach

“…Finally, this work with its mechanistic implications on basic chemistry provides important evidences in the development of an innovative semiclassical model capable of fully describing the quantum state resolved reaction dynamics of prototype oxidation processes such as the chemiionization reactions [44,45].…”