Stereodynamics in the Collisional Autoionization of Water, Ammonia, and Hydrogen Sulfide with Metastable Rare Gas Atoms: Competition Between Intermolecular Halogen and Hydrogen Bonds

Abstract

Recent experiments on the title subject, performed with a high-resolution crossed-beam apparatus, have provided the total ionization cross sections as a function of the collision energy between noble gas atoms, electronically excited in their metastable states (Ng*), and H2 O, H2 S, and NH3 reagents, as well as the emitted electron energy spectra. This paper presents a rationalization of all the experimental findings in a unifying picture to cast light on the basic chemical properties of Ng* under conditions of great relevance both from a fundamental and from an applied point of view. The importance of this investigation is that it isolates the selective role of the intermolecular halogen and hydrogen bonds, to assess their anisotropic effects on the stereodynamics of the promoted ionization reactions, and to model energy transfer and reactivity in systems of applied interest, such as planetary atmospheres, plasmas, lasers, and flames.

Stereoselectivity in Autoionization Reactions of Hydrogenated Molecules by Metastable Noble Gas Atoms: The Role of Electronic Couplings

“…(3–5)] combined with the corresponding real parts V (see refs. , ), provide the optical potential W to be used in practical calculations of the total ionization cross sections for the formation of the product ions in different final electronic states as a function of the polar angles and of the collision energy. Such cross sections, calculated at 70 meV, which represent the average of collision energy probed by our MB experiments, are plotted in the panels of Figures , , and .…”

“…For electron energy spectra determinations, a hemispherical electrostatic selector has been used . This is located above the beam crossing volume in opposite direction with respect to the quadrupole mass spectrometer.…”

The Escape of O^+ and CO^+ Ions from Mars and Titan Atmospheres by Coulomb Explosion of CO22+ Molecular Dications

“…Ionization processes occurring in gas phase and induced by photons, electrons or excited metastable neutral species (also called the Penning ionization, chemiionization, or collisional autoionization reactions [1][2][3]) play an important role in several phenomena taking place in low energy ionized plasmas and electric discharges [4,5]. Moreover, ions are extremely important in the upper atmosphere of planets, where they control the chemistry of ionospheres [6,7].…”

Molecular Fragmentation of Acetylene by VUV Double Photoionization

“…All ionization reactions play an important role in several phenomena occurring in low energy ionized plasmas [3], in the upper atmosphere of planets, where they govern the chemistry of ionospheres [4,5], and in electric discharges [6,7].…”