Cold temperatures invert product ratios in Penning ionisation reactions with argon

In many chemical reactions with more than one possible outcome, the branching ratio, which is the ratio between the different reaction paths, is nearly constant over a wide range of collision energies. In barrierless systems governed by long-range interactions, however, the branching ratio is more s...

Full description

Saved in:
Bibliographic Details
Published inMolecular physics Vol. 117; no. 15-16; pp. 2128 - 2137
Main Authors Bibelnik, Natan, Gersten, Sasha, Henson, Alon B, Lavert-Ofir, Etay, Shagam, Yuval, Skomorowski, Wojciech, Koch, Christiane P, Narevicius, Edvardas
Format Journal Article
LanguageEnglish
Published Abingdon Taylor & Francis 18.08.2019
Taylor & Francis Ltd
Subjects
Argon
Associative ionisation
Branching ratio
Chemical reactions
Cold collisions
Dependence
Energy measurement
Helium
Merged beam
Neon
Organic chemistry
Penning ionisation
Penning ionization
Rangefinding
Online AccessGet full text

Cover

More Information
Summary:In many chemical reactions with more than one possible outcome, the branching ratio, which is the ratio between the different reaction paths, is nearly constant over a wide range of collision energies. In barrierless systems governed by long-range interactions, however, the branching ratio is more sensitive to collision energy, and its dependence on it can be useful for better understanding the dynamics and reconstructing interaction potentials. Here we present the reaction rates of Penning and associative ionisation of metastable neon and helium with argon atoms. We obtain reaction rates in merge beam experiments, over a wide range of collision energies corresponding to that of room temperature, all the way down to a few millikelvins. We observe a change of two orders of magnitude in the branching ratio in the measured collision energy range and explain these changes using theoretical calculations.
ISSN:0026-8976
1362-3028
DOI:10.1080/00268976.2019.1594421