SPECTROSCOPIC PROBING OF LOW-TEMPERATURE ION-MOLECULE REACTIONS

Brünken, Sandra

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https://hdl.handle.net/2142/122385 Copy

Description

Title

SPECTROSCOPIC PROBING OF LOW-TEMPERATURE ION-MOLECULE REACTIONS

Author(s)

Brünken, Sandra

Contributor(s)

• Redlich, Britta
• Marimuthu, Aravindh Nivas
• Schrauwen, Johanna G.M.
• Rap, Daniel

Issue Date

2023-06-22

Keyword(s)

Mini-symposium: Spectroscopy with Cryogenic Ion Traps

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are abundant in many regions of the Universe, representing a major reservoir for cosmic carbon. However, their formation pathways in cold regions of space, such as dense molecular clouds and Titan's atmosphere, remain elusive despite the recent advances in the detection of aromatic molecules there. Astronomical observations show that astrochemical models significantly underestimate the abundance of these aromatic molecules, indicating that efficient formation pathways, such as ion-molecule reactions involving aromatic ions and hydrocarbon neutrals, are likely missing in the existing models. In our work, we use a cryogenic 22-pole ion trap apparatus to study ion-molecule reactions at low temperature, and to structurally identify ionic reactants, reaction intermediates and products in-situ employing infrared-predissociation (IRPD) and infrared multiple-photon dissociation (IRMPD) spectroscopy using the infrared free-electron lasers at the FELIX Laboratory. We reveal efficient low-temperature formation pathways towards PAHs and related species via exothermic ion-molecule reactions. The experimental approach combines kinetic and spectroscopic studies, and unambiguously identifies key reaction intermediates, and, in the case of the reaction of pyridine⁺ with acetylene, the final nitrogen-containing PAH product ion quinolizinium⁺. These studies not only reveal competing formation pathways relevant in cold astronomical environments, but also deliver a variety of information to verify in-silico potential energy surfaces, astronomical models, and to guide infrared observations.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122385

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