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Proceedings Paper

Femtosecond intramolecular dymanics after near-IR excitation of CH3I, C2H5I, CF3CHFI, and C7H8 molecules in the gas phase and in solution
Author(s): Vitaly N. Krylov; Maxim V. Nikitchenko; Martin Quack; Georg Seyfang
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Paper Abstract

The rapid flow of vibrational energy within a molecule is central for the control and as well for the theory of unimolecular reactions. It defines the lifetime of vibrationally excited states and thus the time during which a specific vibrational excitation can control the outcome of chemical reactions. Times for intramolecular vibrational energy redistribution (IVR) can be deduced either indirectly from time-independent high resolution infrared(IR) spectra or measured directly in kinetic pump-probe experiments. We have applied delayed ultraviolet(UV) absorption spectroscopy with a time resolution of 150 fs to measure intramolecular vibrational energy redistribution after near-IR excitation of the CH-stretching vibration around 5900 cm-1 in CF3CHFI, CH3I, C2H5I, and C7H8. Intramolecular relaxation times T(IVR) between 3 and 7 ps have been found in the gas phase. For CH3I an additional short time of 250 fs has been measured. In the liquid phase IVR is followed by a fast collisional energy transfer of the excitation energy to the solvent molecules. Assuming a two step kinetic mechanism intermolecular relaxation times T(transfer) between 10 and 30 ps have been determined.

Paper Details

Date Published: 14 June 2004
PDF: 12 pages
Proc. SPIE 5337, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications III, (14 June 2004); doi: 10.1117/12.530069
Show Author Affiliations
Vitaly N. Krylov, Swiss Federal Institute of Technology Zurich (Switzerland)
State Optical Institute (Russia)
Maxim V. Nikitchenko, Swiss Federal Institute of Technology Zurich (Switzerland)
Martin Quack, Swiss Federal Institute of Technology Zurich (Switzerland)
Georg Seyfang, Swiss Federal Institute of Technology Zurich (Switzerland)


Published in SPIE Proceedings Vol. 5337:
Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications III
Kenneth L. Schepler; Dennis D. Lowenthal, Editor(s)

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