The photodissociation dynamics of jet-cooled trifluoroacetaldehyde (CF3CHO) into radical products, CF3 + HCO, was explored using velocity mapped ion imaging over the wavelength range 297.5 nm 342.8 nm (33 613–29 172 cm−1) covering the entire section of the absorption spectrum accessible with solar actinic wavelengths at the ground level. After initial excitation to the first excited singlet state, S1, the radical dissociation proceeds largely via the first excited triplet state, T1, at excitation energies above the T1 barrier. By combining velocity-mapped ion imaging with high-level theory, we place this barrier at 368.3 ± 2.4 kJ mol−1 (30 780 ± 200 cm−1). After exciting to S1 at energies below this barrier, the dissociation proceeds exclusively via the ground electronic state, S0. The dissociation threshold is determined to be 335.7 ± 1.8 kJ mol−1 (28 060 ± 150 cm−1). Using laser-induced fluorescence spectroscopy, the origin of the S1 ← S0 transition is assigned at 28 903 cm−1. The S0 dissociation channel is active at the S1 origin, but the yield significantly increases above 29 100 cm−1 due to enhanced intersystem crossing or internal conversion.
Photodissociation dynamics of CF3CHO: C–C bond cleavage
Note: This paper is part of the 2021 JCP Emerging Investigators Special Collection.
Jyoti S. Campbell, Klaas Nauta, Scott H. Kable, Christopher S. Hansen; Photodissociation dynamics of CF3CHO: C–C bond cleavage. J. Chem. Phys. 28 November 2021; 155 (20): 204303. https://doi.org/10.1063/5.0073974
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