On the Wavelength-Dependent Photochemistry of the Atmospheric Molecule CFsub3/subCOCl

0578748 - ÚFCH JH 2024 RIV US eng J - Journal Article
Janoš, J. - Vinklárek, Ivo S. - Rakovský, Jozef - Mukhopadhyay, D. P. - Curchod, B. F. E. - Fárník, Michal - Slavíček, P.
On the Wavelength-Dependent Photochemistry of the Atmospheric Molecule CFsub3/subCOCl.
ACS Earth and Space Chemistry. Roč. 7, č. 11 (2023), s. 2275-2286. ISSN 2472-3452. E-ISSN 2472-3452
Institutional support: RVO:61388955
Keywords : absorption cross-sections * quantum yields * cf3c(o)cl * dynamics * spectra * computational photochemistry * conical intersections * excited states * molecular beams * photodissociation * velocity map imaging * photolysis
OECD category: Physical chemistry
Impact factor: 3.4, year: 2022
Method of publishing: Open access

The wavelength control of photochemistry usually results from ultrafast dynamics following the excitation of different electronic states. Here, we investigate the CF3COCl molecule, exhibiting wavelength-dependent photochemistry both via (i) depositing increasing internal energy into a single state and (ii) populating different electronic states. We reveal the mechanism behind the photon-energy dependence by combining nonadiabatic ab initio molecular dynamics techniques with the velocity map imaging experiment. We describe a consecutive mechanism of photodissociation where an immediate release of Cl taking place in an excited electronic state is followed by a slower ground-state dissociation of the CO fragment. The CO release is subject to an activation barrier and is controlled by excess internal energy via the excitation wavelength. Therefore, a selective release of CO along with Cl can be achieved. The mechanism is fully supported by both the measured kinetic energy distributions and anisotropies of the angular distributions. Interestingly, the kinetic energy of the released Cl atom is sensitively modified by accounting for spin-orbit coupling. Given the atmospheric importance of CF3COCl, we discuss the consequences of our findings for atmospheric photochemistry.
Permanent Link: https://hdl.handle.net/11104/0347655