Related Experiment Video
Updated: May 29, 2026
08:51
Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers
Published on: August 18, 2017
Interstellar Stereoisomerism
Víctor M Rivilla1, Miguel Sanz-Novo1, David San Andrés1
1CSIC-INTA, Centro de Astrobiología (CAB), Ctra. de Ajalvir, km. 4, Torrejón de Ardoz, Madrid E-28850, Spain.
ACS Earth & Space Chemistry
|May 28, 2026
Summary
Stereoisomerism is key to interstellar molecular complexity. Observed ratios in space often defy thermodynamic predictions, indicating unique formation and transformation pathways are at play.
Area of Science:
- Astrochemistry
- Interstellar Medium (ISM) Research
- Stereochemistry
Background:
- Increasing detection of novel molecules in the ISM highlights the significance of stereoisomerism.
- Stereoisomers, molecules with the same chemical formula but different spatial arrangements, contribute to molecular complexity.
Purpose of the Study:
- To provide the first comprehensive overview of stereoisomerism in the interstellar medium.
- To analyze observed stereoisomeric ratios (OSRs) and their implications for interstellar chemistry.
Main Methods:
- Identification and analysis of 16 stereoisomeric pairs (13 conformational, 3 geometric) across diverse astrophysical environments.
- Comparison of observed stereoisomeric ratios with thermodynamic expectations.
Main Results:
- Stereoisomers were found in molecules with 5-12 atoms, with energy separations from ~10 K to 2667 K.
- Observed stereoisomeric ratios (OSRs) varied widely (0.009-4) across different kinetic temperatures (7.5-300 K).
- Many stereoisomers, especially in cold clouds or with large energy gaps, showed abundances exceeding equilibrium, defying thermodynamic predictions.
Conclusions:
- Thermodynamics alone cannot explain interstellar stereoisomerism; stereoselective pathways (gas-phase, grain-surface), photoisomerization, and desorption processes are crucial.
- Stereoisomeric ratios offer vital constraints on ISM chemical pathways and conditions.
- Further research requires enhanced laboratory spectroscopy, quantum chemical studies, and stereochemistry-inclusive astrochemical models.
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