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Coherently excited vibrational modes reveal reaction mechanism
In many cases transient absorption studies with extremely high time resolution show strong oscillatory signal contributions. E. g. the figure below shows the time resolved trans mission change due to the excited state proton transfer of 2-(2'-hydroxyphenyl)benzothiazole (HBT). The signal oscillations reflect periodic shifts of the emission and excited state absorption spectra caused by coherently excited vibrations.
To identify the vibrational modes which are excited we compare the frequencies appearing in the time resolved data with infrared spectra and ab-initio calculations. The phase of the oscillation pattern indicates when the vibration is excited in the process. This tells us what role the various molecular coordinates play and allows us to reconstruct the reaction path.
The signal rise after time zero and the contrast ratio of the oscillatory contributions reflect the evolution, broadening and dephasing of the wavepacket. This allows to discriminate between a ballistic and a rate governed behavior.
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| Former co-workers: Kai Stock, Alexander Wurzer | |
"Ultrafast proton transfer of 1-hydroxy-2-acetonaphthone: Reaction path from resonance Raman and transient absorption studies"
S. Lochbrunner, A. Szeghalmi, K. Stock, and M. Schmitt
J. Chem. Phys. 122, 244315 (2005)
Details
"Direct observation of the nuclear motion during
ultrafast intramolecular proton transfer"
S. Lochbrunner, K. Stock, and E. Riedle
J. Mol. Struct. 700, 13 - 18 (2004)
Details
"The microscopic mechanism of ultrafast excited state
intramolecular proton transfer:
a 30 fs study of 2-(2'-hydroxyphenyl)benzothiazole"
S. Lochbrunner, A. J. Wurzer, and E. Riedle
J. Phys. Chem. A 107, 10580 - 10590 (2003)
Details
"Exploring the multidimensional character of ultrafast molecular processes"
S. Lochbrunner and E. Riedle
Recent Res. Devel. Chem. Physics 4, 31 - 61 (2003)
Details
"Proton transfer and internal conversion of o-hydroxybenzaldyde: Coherent versus statistical excited state
dynamics"
K. Stock, T. Bizjak, and S. Lochbrunner
Chem. Phys. Lett. 354 (2002), 409-416
Details
"Ultrafast excited state proton transfer and subsequent coherent skeletal motion of 2-(2'-hydroxyphenyl)benzothiazole"
S. Lochbrunner, A. J. Wurzer, E. Riedle
J. Chem. Phys. 112, 10699 - 10702 (2000)
Details
"Highly localized vibronic wavepackets in large reactive molecules"
A. J. Wurzer, S. Lochbrunner, E. Riedle
Applied Physics B 71, 405 - 409 (2000)
Details
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