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Features of the fluorine‐substituted acetaldehydes dynamics in the low‐lying electronic states: Quantum mechanical study of the CHF2CHO molecule lowest excited singlet state

“…and CCO (def.) vibrations are close to the experimental ones 3, 4 for the states T 1 and S 1 , just as for the torsional (T 1 ) motion. Discrepancy is slightly larger for the CF 2 sciss.…”

“…6). It is worth noting that experimental data on infrared (IR) and vibronic spectra agree with the calculated stability of the one conformation of CHF 2 CHO (S 0 ) only 3, 4, 6.…”

“…The vibrational frequencies estimated in harmonic approximation are given in Table IV for CHF 2 CHO (S 1 ) in comparison with those for S 0 and T 1 states 6. The experimental data 4 are in agreement with the calculated data. As clear from the electronic structure modifications under the (S 1 , T 1 ) ← S 0 excitation above mentioned, the frequencies of the valence CO and deformational CCO vibrations decrease in accordance with the experimental and theoretical data for the carbonyl compounds 6, 9.…”

“…As a result, the potential energy surfaces for the excited states of these molecules have a more complex form than for the ground state and the relative vibronic spectra are complicated 3, 4. It is worth noting the similarity in the PES structures for the S 1 and T 1 excited states of the same molecule.…”

“…Special attention is paid to the CHF 2 CHO (S 1 ) molecule being an example for all considerations here. Earlier we studied the structure of CF 3 CHO 1, 2 and CHF 2 CHO 3, 4 molecules in the excited S 1 and T 1 electronic states by methods of vibronic spectroscopy. We also have used quantum mechanical calculations to investigate the structure of CH 2 FCHO (S 0 , S 1 , T 1 ) 5, CHF 2 CHO (S 0 , T 1 ) 6, and CF 3 CHO (S 0 ) 7.…”