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.

Centre for Computational Chemistry School of Chemistry University of Bristol Bristol BS8 1TS U K

Department of Dynamics of Molecules and Clusters J Heyrovský Institute of Physical Chemistry v v i The Czech Academy of Sciences Dolejškova 2155 3 182 23 Prague Czech Republic

Department of Physical Chemistry University of Chemistry and Technology Technická 5 Prague 6 166 28 Czech Republic

See more in PubMed

Francisco J. Dissociation dynamics of CF3C(O)X compounds (where X= H, F and Cl). Chem. Phys. 1992, 163, 27–36. 10.1016/0301-0104(92)80136-J. DOI

Burkholder J. B.; Cox R.; Ravishankara A. Atmospheric degradation of ozone depleting substances, their substitutes, and related species. Chem. Rev. 2015, 115, 3704–3759. 10.1021/cr5006759. PubMed DOI

Rattigan O.; Wild O.; Jones R.; Cox R. Temperature-dependent absorption cross-sections of CF3COCl, CF3COF, CH3COF, CCl3CHO and CF3COOH. J. Photochem. Photobiol., A 1993, 73, 1–9. 10.1016/1010-6030(93)80026-6. DOI

Maricq M. M.; Szente J. J. The 193 and 248 nm Photodissociation of CF3C(O)Cl. J. Phys. Chem. 1995, 99, 4554–4557. 10.1021/j100013a028. DOI

McGillen M. R.; Burkholder J. B. Gas-phase photodissociation of CF3C(O)Cl between 193 and 280 nm. Chem. Phys. Lett. 2015, 639, 189–194. 10.1016/j.cplett.2015.09.024. DOI

Durig J.; Fanning A.; Sheehan T.; Guirgis G. Far-infrared spectra and barriers to internal rotation for the CF3CXO molecules where X= H, F, Cl, Br, CH3 and CF3. Spectrochim. Acta, Part A 1991, 47, 279–289. 10.1016/0584-8539(91)80100-W. DOI

Meller R.; Moortgat G. K. CF3C(O)Cl: Temperature-dependent (223–298 K) absorption cross-sections and quantum yields at 254 nm. J. Photochem. Photobiol., A 1997, 108, 105–116. 10.1016/S1010-6030(97)00094-4. DOI

Berney C. V. Infrared, Raman and near-ultraviolet spectra of CF3COZ compounds—II. Hexafluoroacetone. Spectrochim. Acta 1965, 21, 1809–1823. 10.1016/0371-1951(65)80093-5. DOI

Berney C. Spectroscopy of CF3COZ compounds—IV: Vibrational spectrum of trifluoroacetyl fluoride. Spectrochim. Acta, Part A 1971, 27, 663–672. 10.1016/0584-8539(71)80064-8. DOI

Gobbato K. I.; Leibold C.; Centeno S.; Della Védova C. O.; Mack H.-G.; Oberhammer H. Gas phase structures of trifluoroacetyl chloride, CF3C(O)Cl, and chlorodifluoroacetyl chloride, CF2ClC(O)Cl. J. Mol. Struct. 1996, 380, 55–61. 10.1016/0022-2860(95)09187-4. DOI

Hao Y.; Liu L.; Fang W.-H. Photo-dissociation mechanism of trifluoroacetyl chloride in the gas phase: AIMS dynamic simulations. J. Chem. Phys. 2021, 154, 244303.10.1063/5.0046451. PubMed DOI

Ma X.; Tian H. Photochemistry and Photophysics. Concepts, Research, Applications. By Vincenzo Balzani, Paola Ceroni and Alberto Juris. Angew. Chem. 2014, 126, 8961.10.1002/ange.201405219. DOI

Kasha M. Characterization of electronic transitions in complex molecules. Discuss. Faraday Soc. 1950, 9, 14–19. 10.1039/df9500900014. DOI

Mignolet B.; Curchod B. F. E.; Martínez T. J. Rich Athermal Ground-State Chemistry Triggered by Dynamics through a Conical Intersection. Angew. Chem. 2016, 128, 15217–15220. 10.1002/ange.201607633. PubMed DOI

Pathak S.; Ibele L. M.; Boll R.; Callegari C.; Demidovich A.; Erk B.; Feifel R.; Forbes R.; Di Fraia M.; Giannessi L.; et al. Tracking the ultraviolet-induced photochemistry of thiophenone during and after ultrafast ring opening. Nat. Chem. 2020, 12, 795–800. 10.1038/s41557-020-0507-3. PubMed DOI

Slavíček P.; Fárník M. Photochemistry of hydrogen bonded heterocycles probed by photodissociation experiments and ab initio methods. Phys. Chem. Chem. Phys. 2011, 13, 12123–12137. 10.1039/c1cp20674e. PubMed DOI

Salter R. J.; Blitz M. A.; Heard D. E.; Kovács T.; Pilling M. J.; Rickard A. R.; Seakins P. W. Quantum yields for the photolysis of glyoxal below 350 nm and parameterisations for its photolysis rate in the troposphere. Phys. Chem. Chem. Phys. 2013, 15, 4984–4994. 10.1039/c3cp43597k. PubMed DOI

Prlj A.; Ibele L. M.; Marsili E.; Curchod B. F. E. On the theoretical determination of photolysis properties for atmospheric volatile organic compounds. J. Phys. Chem. Lett. 2020, 11, 5418–5425. 10.1021/acs.jpclett.0c01439. PubMed DOI PMC

Lauer A.; Fast D. E.; Steinkoenig J.; Kelterer A.-M.; Gescheidt G.; Barner-Kowollik C. Wavelength-Dependent Photochemical Stability of Photoinitiator-Derived Macromolecular Chain Termini. ACS Macro Lett. 2017, 6, 952–958. 10.1021/acsmacrolett.7b00499. PubMed DOI

Dietzek B.; Fey S.; Matute R. A.; González L.; Schmitt M.; Popp J.; Yartsev A.; Hermann G. Wavelength-dependent photoproduct formation of phycocyanobilin in solution – Indications for competing reaction pathways. Chem. Phys. Lett. 2011, 515, 163–169. 10.1016/j.cplett.2011.08.086. DOI

Fedor J.; Kočišek J.; Poterya V.; Votava O.; Pysanenko A.; Lipciuc L.; Kitsopoulos T. N.; Fárník M. Velocity Map Imaging of HBr Photodissociation in Large Rare Gas Clusters. J. Chem. Phys. 2011, 134, 154303.10.1063/1.3578610. PubMed DOI

Eppink A. T. J. B.; Parker D. H. Velocity map imaging of ions and electrons using electrostatic lenses: Application in photoelectron and photofragment ion imaging of molecular oxygen. Rev. Sci. Instrum. 1997, 68, 3477–3484. 10.1063/1.1148310. DOI

Whitaker B.Imaging in Molecular Dynamics; Cambridge University Press: Cambridge, 2003.

Vinklárek I. S.; Rakovský J.; Poterya V.; Fárník M. Different Dynamics of CH3 and Cl Fragments from Photodissociation of CH3Cl in Clusters. J. Phys. Chem. A 2020, 124, 7633–7643. 10.1021/acs.jpca.0c05926. PubMed DOI

Vinklárek I. S.; Suchan J.; Rakovský J.; Moriová K.; Poterya V.; Slavíček P.; Fárník M. Energy partitioning and spin–orbit effects in the photodissociation of higher chloroalkanes. Phys. Chem. Chem. Phys. 2021, 23, 14340–14351. 10.1039/D1CP01371H. PubMed DOI

Gibson S.; Hickstein D. D.; Yurchak R.; Ryazanov M.; Das D.; Shih G.. PyAbel/PyAbel, v0.8.5, 2022.

Shiozaki T.; Győrffy W.; Celani P.; Werner H.-J. Communication: Extended multi-state complete active space second-order perturbation theory: Energy and nuclear gradients. J. Chem. Phys. 2011, 135, 081106.10.1063/1.3633329. PubMed DOI

Slavíček P.; Martínez T. J. Ab initio floating occupation molecular orbital-complete active space configuration interaction: An efficient approximation to CASSCF. J. Chem. Phys. 2010, 132, 234102.10.1063/1.3436501. PubMed DOI

Hollas D.; Šištík L.; Hohenstein E. G.; Martínez T. J.; Slavíček P. Nonadiabatic Ab Initio Molecular Dynamics with the Floating Occupation Molecular Orbital-Complete Active Space Configuration Interaction Method. J. Chem. Theory Comput. 2018, 14, 339–350. 10.1021/acs.jctc.7b00958. PubMed DOI

Fales B. S.; Hohenstein E. G.; Levine B. G. Robust and Efficient Spin Purification for Determinantal Configuration Interaction. J. Chem. Theory Comput. 2017, 13, 4162.10.1021/acs.jctc.7b00466. PubMed DOI

Suchan J.; Hollas D.; Curchod B. F. E.; Slavíček P. On the importance of initial conditions for excited-state dynamics. Faraday Discuss. 2018, 212, 307–330. 10.1039/C8FD00088C. PubMed DOI

Werner H.-J.; Knowles P. J.; Knizia G.; Manby F. R.; Schütz M. Molpro: a General Purpose Quantum Chemistry Program Package. Wiley Interdiscip. Rev.: Comput. Mol. Sci. 2012, 2, 242–253. 10.1002/wcms.82. DOI

Aquilante F.; Autschbach J.; Baiardi A.; Battaglia S.; Borin V. A.; Chibotaru L. F.; Conti I.; De Vico L.; Delcey M.; Fdez. Galván I.; et al. Modern quantum chemistry with [open]molcas. J. Chem. Phys. 2020, 152, 214117.10.1063/5.0004835. PubMed DOI

Fdez Galván I.; Vacher M.; Alavi A.; Angeli C.; Aquilante F.; Autschbach J.; Bao J. J.; Bokarev S. I.; Bogdanov N. A.; Carlson R. K.; et al. OpenMolcas: From Source Code to Insight. J. Chem. Theory Comput. 2019, 15, 5925–5964. 10.1021/acs.jctc.9b00532. PubMed DOI

Frisch M. J.; et al.Gaussian 09, Revision D.01; Gaussian Inc.: Wallingford CT, 2009.

Ufimtsev I. S.; Martinez T. J. Quantum Chemistry on Graphical Processing Units. 3. Analytical Energy Gradients, Geometry Optimization, and First Principles Molecular Dynamics. J. Chem. Theory Comput. 2009, 5, 2619–2628. 10.1021/ct9003004. PubMed DOI

Titov A. V.; Ufimtsev I. S.; Luehr N.; Martinez T. J. Generating Efficient Quantum Chemistry Codes for Novel Architectures. J. Chem. Theory Comput. 2013, 9, 213–221. 10.1021/ct300321a. PubMed DOI

Sršeň Š.; Sita J.; Slavíček P.; Ladányi V.; Heger D. Limits of the Nuclear Ensemble Method for Electronic Spectra Simulations: Temperature Dependence of the (E)-Azobenzene Spectrum. J. Chem. Theory Comput. 2020, 16, 6428–6438. 10.1021/acs.jctc.0c00579. PubMed DOI

Suchan J.; Janoš J.; Slavíček P. Pragmatic Approach to Photodynamics: Mixed Landau–Zener Surface Hopping with Intersystem Crossing. J. Chem. Theory Comput. 2020, 16, 5809–5820. 10.1021/acs.jctc.0c00512. PubMed DOI

Belyaev A. K.; Lasser C.; Trigila G. Landau–Zener type surface hopping algorithms. J. Chem. Phys. 2014, 140, 224108.10.1063/1.4882073. PubMed DOI

Ma X.-R.; Zhang J.; Xiong Y.-C.; Zhou W. Revising the performance of the Landau–Zener surface hopping on some typical one-dimensional nonadiabatic models. Mol. Phys. 2022, 120, 120.10.1080/00268976.2022.2051761. DOI

Hollas D.; Suchan J.; Svoboda O.; Ončák M.; Slavíček P.. ABIN, 2018.

Vinklárek I. S.; Rakovský J.; Poterya V.; Fárník M. Clustering and multiphoton effects in velocity map imaging of methyl chloride. Mol. Phys. 2021, 119, e182350710.1080/00268976.2020.1823507. DOI

Rowell K. N.; Kable S. H.; Jordan M. J. T. Structural Effects on the Norrish Type I α-Bond Cleavage of Tropospherically Important Carbonyls. J. Phys. Chem. A 2019, 123, 10381–10396. 10.1021/acs.jpca.9b05534. PubMed DOI

Hansen C.; Campbell J.; Kable S. Photodissociation of CF3CHO provides a new source of CHF3 (HFC-23) in the atmosphere: implications for new refrigerants. Res. Sq. 2021, 10.21203/rs.3.rs-199769/v1. DOI

Sensitivity Analysis in Photodynamics: How Does the Electronic Structure Control cis-Stilbene Photodynamics?