Ultrafast Dynamics of Acetylacetone (2,4-Pentanedione) in the S2 State
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- 作者：Lionel Poisson ; Pascale Roubin ; Sté ; phane Coussan ; Benoî ; t Soep ; Jean-Michel Mestdagh
- 刊名：Journal of the American Chemical Society
- 出版年：2008
- 出版时间：March 12, 2008
- 年：2008
- 卷：130
- 期：10
- 页码：2974 - 2983
- 全文大小：229K
- 年卷期：v.130,no.10(March 12, 2008)
- ISSN：1520-5126
文摘
The dynamics of the enolic form of acetylacetone (E-AcAc) was investigated using a femtosecondpump-probe experiment. The pump at 266 nm excited E-AcAc in the first bright state, S2(
*). The resultingdynamics was probed by multiphoton ionization at 800 nm. It was investigated for 80 ps on the S2(*)and S1(n*) potential energy surfaces. An important step is the transfer from S2 to S1 that occurs with atime constant of 1.4 ± 0.2 ps. Before, the system had left the excitation region in 70 ± 10 fs. An intermediatestep was identified when E-AcAc traveled on the S2 surface. Likely, it corresponds to an accidental resonancein the detection scheme that is met along this path. More importantly, some clues are given that anintramolecular vibrational energy relaxation is observed, which transfers excess vibrational energy fromthe enolic group O-H to the other modes of the molecule. The present multistep evolution of excited E-AcAcprobably also describes, at least qualitatively, the dynamics of other electronically excited 
-diketones.
*). The resultingdynamics was probed by multiphoton ionization at 800 nm. It was investigated for 80 ps on the S2(*)and S1(n*) potential energy surfaces. An important step is the transfer from S2 to S1 that occurs with atime constant of 1.4 ± 0.2 ps. Before, the system had left the excitation region in 70 ± 10 fs. An intermediatestep was identified when E-AcAc traveled on the S2 surface. Likely, it corresponds to an accidental resonancein the detection scheme that is met along this path. More importantly, some clues are given that anintramolecular vibrational energy relaxation is observed, which transfers excess vibrational energy fromthe enolic group O-H to the other modes of the molecule. The present multistep evolution of excited E-AcAcprobably also describes, at least qualitatively, the dynamics of other electronically excited -diketones.