What the study found
The study found that two Criegee intermediates, H2COO and CH3CHOO, behave differently depending on whether they are in the gas phase, in water droplets, on amorphous solid water, or in bulk water. In water droplets, both species can move easily between the surface and the interior, while on amorphous solid water at 50 K there was no observed surface diffusion over multiple nanoseconds.
Why the authors say this matters
The authors say the infrared spectroscopy results show shifts in aqueous environments that are consistent with Stark-induced spectral shifts, which are shifts caused by an electric field, as seen for small molecules in protein environments. They also note that the droplet spectroscopy does not depend on whether the intermediates are inside the droplet or on its surface.
What the researchers tested
The researchers used validated energy functions to investigate the dynamics and infrared spectroscopy of the small and large Criegee intermediates. They examined these molecules in the gas phase, inside and on water droplets, on amorphous solid water, and in bulk water.
What worked and what didn't
For both intermediates, diffusion between surface and interior positions in water droplets was facile. On amorphous solid water at 50 K, surface diffusion was not observed on the multiple-nanosecond timescale, unlike what has been reported for species such as CO or NO on amorphous solid water. Infrared spectral features shifted by a few to a few tens of units, depending on the vibrational mode, when the molecules were in contact with an aqueous environment.
What to keep in mind
The abstract does not provide experimental details beyond the use of validated energy functions, and it does not state additional limitations. The reported results are specific to the two Criegee intermediates and the environments listed in the abstract.
Key points
- Two Criegee intermediates, H2COO and CH3CHOO, were studied in gas and aqueous environments.
- Both molecules showed easy movement between surface and interior positions in water droplets.
- No surface diffusion was observed on amorphous solid water at 50 K over multiple nanoseconds.
- Infrared spectral features shifted in aqueous environments by a few to a few tens of units, depending on the mode.
- Droplet spectroscopy did not depend on whether the molecule was inside the droplet or on the surface.
Disclosure
- Research title:
- Criegee intermediates behave differently at water interfaces
- Authors:
- Cangtao Yin, Meenu Upadhyay, Markus Meuwly
- Institutions:
- University of Basel, University of Basel, University of Basel
- Publication date:
- 2026-04-26
- OpenAlex record:
- View
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