The geometrical change and intramolecular energy transfer upon S{sub 1}←S{sub 0} excitation in cyclopentanone
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)
The ultrafast dynamics in vibrationally hot S{sub 1} electronic excited state in cyclopentanone molecule was discovered with time resolved spectroscopy. Investigation of the geometry change upon the S{sub 1}←S{sub 0} excitation and D{sub 0}←S{sub 1} ionization has shown that the dihedral angle between the C=O bond and the plane given by the carbonyl and the α-carbons is 180° either in S{sub 0} or D{sub 0} state and is reduced to 145.8° by out-out-plane deformation of the oxygen in S{sub 1} state according to the theoretical calculation. The time domain experiments with femtosecond resolution have given rich insights into the energy transfer of the cyclopentanone molecule. The molecules are excited to the vibrationally hot S{sub 1} (n, π{sup ∗}) state following absorption of one 267-nm photon. It is found that the population of the S{sub 1} (n, π{sup ∗}) state undergoes ultrafast internal conversion to the highly vibrationally hot S{sub 0} state within 80 fs and nonradiative deactivation by intersystem crossing to triplet T{sub 1} (n, π{sup *}) state occurring in 3.14 ps. Several Rydberg states have worked as stepping stones during the ionization. The available energy was distributed in the symmetric methylene group wagging and the symmetric skeletal ring breathing modes in D{sub 0} state.
- OSTI ID:
- 22493505
- Journal Information:
- Journal of Chemical Physics, Vol. 143, Issue 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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