What the study found
The study found that the dynamics and infrared spectroscopy of two Criegee intermediates, H2COO and CH3CHOO, depend on the surrounding environment. In water droplets, both species can move easily between surface and interior positions, while on amorphous solid water at 50 K there is no observed surface diffusion over multiple nanoseconds.
Why the authors say this matters
The authors indicate that the results help describe how these intermediates behave in gas- and aqueous environments. They also note that the observed spectral shifts in water are consistent with Stark-induced spectral shifts, meaning shifts caused by electric fields, as seen for small molecules in protein environments.
What the researchers tested
The researchers investigated the dynamics and spectroscopy of the small and large Criegee intermediates in the gas phase, inside and on water droplets, on amorphous solid water, and in bulk water. They used validated energy functions to study both species across these environments.
What worked and what didn't
Facile diffusion between surface and interior positions was found for both species in water droplets. On amorphous solid water at 50 K, no surface diffusion was observed on the multiple-nanosecond time scale, which the abstract says differs from species such as CO or NO on amorphous solid water.
For infrared spectroscopy, contact with an aqueous environment led to shifts of the spectral features by a few to a few tens of unspecified units, depending on the vibrational mode. The spectroscopy of both intermediates in water droplets did not depend on whether they were inside the droplet or at the surface.
What to keep in mind
The abstract does not describe limitations beyond the environments and time scales studied. It also does not provide the missing unit for the reported spectral shifts in the text available here.
Key points
- Two Criegee intermediates, H2COO and CH3CHOO, were studied in gas, droplet, surface, and bulk-water environments.
- Both species showed facile movement between the surface and interior of water droplets.
- No surface diffusion was observed on amorphous solid water at 50 K over multiple nanoseconds.
- Aqueous environments shifted infrared spectral features by a few to a few tens of unspecified units, depending on vibrational mode.
- In water droplets, the spectroscopy did not depend on whether the intermediates were inside the droplet or at the surface.
Disclosure
- Research title:
- Criegee intermediates show environment-dependent spectral shifts
- Authors:
- Cangtao Yin, Meenu Upadhyay, Markus Meuwly
- Institutions:
- University of Basel
- Publication date:
- 2026-04-26
- OpenAlex record:
- View
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