The lowest-lying singlet states of the simplest Criegee intermediate (CH2OO) have been characterized along the O-O dissociation coordinate using explicitly correlated MRCI-F12 electronic structure theory and large active spaces. It is found that a high-level treatment of dynamic electron-correlation is essential to accurately describe these states. a significant well on the B-state is identified at the MRCI-F12 level with an equilibrium structure that differs substantially from that of the ground X-state. This well is presumably responsible for the apparent vibrational structure in some experimental UV absorption spectra, analogous to the structured Huggins band of the iso-electronic ozone. the B-state potential in the Franck-Condon region is sufficiently accurate that an absorption spectrum calculated with a one-dimensional model agrees remarkably well with experiment.
- Absorption spectra,
- Electromagnetic wave absorption,
- Electronic structure,
- Light absorption,
- Photodissociation,
- Criegee intermediates,
- Electronic structure theory,
- Equilibrium structures,
- High-level treatment,
- Lowest-lying singlet state,
- One-dimensional model,
- UV absorption spectrum,
- Vibrational structures,
- Absorption spectroscopy,
- formaldehyde,
- alkene,
- ozone,
- Article,
- calculation,
- dissociation,
- experimental study,
- geometry,
- simplest criegee intermediate,
- ultraviolet spectroscopy,
- chemistry,
- photochemistry,
- ultraviolet spectrophotometry,
- Alkenes,
- Ozone,
- Photochemical Processes,
- Spectrophotometry, Ultraviolet
Available at: http://works.bepress.com/richard_dawes/44/