Molecular hydrogen formation on interstellar PAHs through Eley-Rideal abstraction reactions

Journal article (2018)

Authors

Nolan Foley University Medical Center Groningen
S.M. Cazaux Universiteit Leiden, Astrodynamics & Space Missions - Aerospace Engineering
D. Egorov University Medical Center Groningen
Leon Boschman University Medical Center Groningen, Rijksuniversiteit Groningen
R Hoekstra University Medical Center Groningen
Thomas Schlathölter University Medical Center Groningen
Research Group
Astrodynamics & Space Missions (Aerospace Engineering) (TU Delft)
Astrochemistry ISM: molecules Molecular processes
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Published Date

01-09-2018

Language

English

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Faculty

Aerospace Engineering

Department

Space Engineering

Research Group

Astrodynamics & Space Missions

Abstract

We present experimental data on H2 formation processes on gas-phase polycyclic aromatic hydrocarbon (PAH) cations. This process was studied by exposing coronene radical cations, confined in a radio-frequency ion trap, to gas-phase H atoms. Sequential attachment of up to 23 hydrogen atoms has been observed. Exposure to atomic D instead of H allows one to distinguish attachment from competing abstraction reactions, as the latter now leave a unique fingerprint in the measured mass spectra. Modelling of the experimental results using realistic cross-sections and barriers for attachment and abstraction yield a 1:2 ratio of abstraction to attachment cross-sections. The strong contribution of abstraction indicates that H2 formation on interstellar PAH cations is an order of magnitude more relevant than previously thought.