Measurement of Reaction Cross Sections of Ion-Molecule Reactions, Effects of Internal and Collision Energy for Astrochemistry and Industrial Plasma Chemistry
Christian Alcaraz (Senior Researcher), Claire Romanzin (Associate Prof), Roland Thissen (Senior Researcher), Nicolas Solem (PhD Student)
The CERISES platform, associated with the DESIRS beamline of the SOLEIL synchrotron provides a unique approach for the detailed description of the reactive dynamics of small molecular systems. This enables the simulation of elementary acts as they may occur in planetary atmospheres or the interstellar medium, while also providing absolute reaction cross sections.
By utilizing a radical source, the team has successfully reacted CH3+ in an adjustable internal energy state with small oxygenated molecules. They have also investigated the effects of selected states on the reactivity of O2+ with small hydrocarbons and volatile organic compounds, and explored the effect of isomerism by comparing the reactivity of HCO+ and COH+.
Notable results from these studies include
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- Measurement of the Absolute Cross Section for the Formation of SH+: After the collision between S+ and H2, which holds significant astrophysical interest.
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Integral cross section for the reaction S+ + H2 → HS+. The red line corresponds to experimental data, and the black lines represent the theoretical cross sections for the formation of SH+.. [Zanchet2024]
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- Innovative Method for Highlighting Collision-Induced Isomerization of an Ion.
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Differences in time-of-flight spectra recorded in the CERISES instrument for the reaction between the ion HOC+ and four neutral targets, allowing for the highlighting and quantification of a collision-induced isomerization process. [Solem2024]
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- Structure of C8H6+ Isomers as a Function of Ion Internal Energy: Revisited by studying their reactivity with two neutral targets, propyne and allene.
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Absolute reaction cross sections for the formation of a mass 115 ion by reacting C8H6+ with allene. The three colors correspond to the precursor of C8H6+, which can be either phenylacetylene (red), naphthalene (yellow), or azulene (green). [Rossi2024]
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- Combined Theoretical and Experimental Study of the Differentiated Reactivity of Two Isomers H2CNH+ and HCNH2+ with Propene.
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Absolute reaction cross sections for the two ionic isomers HCNH2+ and H2CNH+ with propene as a function of collision energy. The colors correspond to the different observed products. [Richardson2024]
Collaborations
Daniela Ascenzi (University of Trento, Italy), Miroslav Polasek and Jan Zabka (Heyrovsky Institute of Physical Chemistry, Prague, Czech Republic), Wolf Geppert (Stockholm University, Sweden), Emilie Zins (MONARIS, Sorbonne University, Paris), Ugo Jacovella (ISMO, U P Saclay), Stéphane Pasquiers (LPGP, U P Saclay), Alexandre Zanchet (Complutense University of Madrid, Spain), Karoly Vekey (Budapest University, Hungary), James Lyons (Arizona State University, USA).