Experimental Characterization of the Energetics of Low-temperature Surface Reactions

TL;DR

This paper introduces an experimental technique to measure the energy released in low-temperature astrochemical surface reactions, improving understanding of reaction pathways and energy barriers relevant to complex organic molecule formation.

Contribution

The study presents a novel method for directly measuring reaction energetics of single reactant pairs, enhancing the accuracy of astrochemical reaction predictions compared to gas-phase analyses.

Findings

Revealed formation of HCH, CO + O, and cyclic-C3H2 in reactions of C with H2, O2, and C2H2.

Demonstrated the method's ability to compare experimental data with quantum chemical calculations.

Provided insights into reaction pathways and energy barriers on dust grain surfaces.

Abstract

Astrochemical surface reactions are thought to be responsible for the formation of complex organic molecules, which are of potential importance for the origin of life. In a situation, when the chemical composition of dust surfaces is not precisely known, the fundamental knowledge concerning such reactions gains significance. We describe an experimental technique, which can be used to measure the energy released in reactions of a single pair of reactants. These data can be directly compared with the results of quantum chemical computations leading to unequivocal conclusions regarding the reaction pathways and the presence of energy barriers. It allows for predicting the outcomes of astrochemical surface reactions with higher accuracy compared to that achieved based on gas-phase studies. However, for the highest accuracy, some understanding of the catalytic influence of specific surfaces on the reactions is required. The new method was applied to study the reactions of C atoms with H2, O2, and C2H2. The formation of HCH, CO + O, and triplet cyclic-C3H2 products has been revealed, correspondingly.