Kus, J. A., Hüter, O. and Temps, F. (2017) Real-time observation of multi-mode vibronic coherence in pentafluoropyridine. The Journal of Chemical Physics, 147 (1). 013938. DOI 10.1063/1.4983306.

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Abstract

The ultrafast dynamics of pentafluoropyridine in the 1 1B2 (ππ*) electronic state excited at λpump = 255 nm is investigated by femtosecond time-resolved time-of-flight mass spectrometry and photoelectron imaging spectroscopy. A pronounced, long-lived, and complex periodic modulation of the transient ion yield signal with contributions by four distinct frequency components, 72 cm−1, 144 cm−1, 251 cm−1, and 281 cm−1, is observed for up to 9 ps. The recorded photoelectron images display a spectral band from the excited 1 1B2 (ππ*) state only in the oscillation maxima; the signal is strongly reduced in the oscillation minima. Supported by electronic structure calculations at the RI-SCS-CC2 and XMCQDPT2 levels of theory, the oscillating components of the signal are identified as frequencies of b1 symmetry coupling modes in a vibronic coherence of the 1 1B2 (ππ*) and 1 1A2 (πσ*) electronic states. The optical excitation initiates regular and periodic wavepacket motion along those out-of-plane modes. In the distorted molecular structure, the initially excited state acquires substantial πσ* character that modulates the transition dipole moment for ionization and results in the observed oscillations.

Document Type:	Article
Research affiliation:	Kiel University > Kiel Marine Science OceanRep > The Future Ocean - Cluster of Excellence Kiel University
Refereed:	Yes
Open Access Journal?:	No
Publisher:	American Institute of Physics
Projects:	Future Ocean
Date Deposited:	21 Dec 2017 12:53
Last Modified:	06 May 2019 10:41
URI:	https://oceanrep.geomar.de/id/eprint/41100

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