Basic features of Ne*–HX (X = Cl, Br) chemi-ionization reactions

Abstract

Ionization cross sections for Ne*(3P2,0)–HX (X = Cl, Br) chemi-ionizations are presented in the 0.02–0.5 eV collision energy range.

The role of precursor states in the stereo-dynamics of elementary processes

“…Recently, our interest focused on Ne* + HCl, and Ne*+ HBr reactions that show a strong stereo-selectivity. 129 In particular, they promote the formation of parent ions in the ground electronic state, via precursor states having perpendicular configurations, and the formation of parent ions in the first excited electronic state, via precursor states in parallel configurations. The latter can trigger also proton transfer phenomena with the formation of NeH + + X (Cl, Br) products.…”

“…Major details on the stereo-dynamics of such atom–molecule reactions have been reported in a recent paper. 129…”

“…Moreover, Ne* in the |2,2i quantum state involves the half-filled atomic orbital aligned perpendicularly to R. The direct mechanism is forbidden and the reaction occurs only via an indirect mechanism for which most efficient collisions are those with N 2 aligned parallel or near parallel to R. 122 Recently, our interest focused on Ne* + HCl, and Ne*+ HBr reactions that show a strong stereo-selectivity. 129 In particular, they promote the formation of parent ions in the ground electronic state, via precursor states having perpendicular configurations, and the formation of parent ions in the first excited electronic state, via precursor states in parallel configurations. The latter can trigger also proton transfer phenomena with the formation of NeH + + X (Cl, Br) products.…”

“…Major details on the stereodynamics of such atom-molecule reactions have been reported in a recent paper. 129 Fig. 16 Upper panel: Comparison, as a function of the collision energy, between predicted associative/Penning ratio for Ne*( 3 P 2 ) (red line) and Ne*( 3 P 0 ) (black line) reagents and data measured 127 using a statistical population of atomic fine levels.…”

Differential ionization cross-section of hydrogen bromide

“…The ionization processes occurring on HX molecules, where X is a halogen atom, induced by collisions with rare gas metastable atoms have attracted great interest from the scientific community since they are of relevance in the development of excimer lasers. 5 Hydrogen bromide has an important role in the plasma etching of polysilicon with the combination of HCl and Chlorine. Many theoretical studies are there for the absolute ionization cross-section of the HBr molecule.…”