14 June 2004 Femtosecond intramolecular dymanics after near-IR excitation of CH3I, C2H5I, CF3CHFI, and C7H8 molecules in the gas phase and in solution
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Proceedings Volume 5337, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications III; (2004) https://doi.org/10.1117/12.530069
Event: Lasers and Applications in Science and Engineering, 2004, San Jose, Ca, United States
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.
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Vitaly N. Krylov, Maxim V. Nikitchenko, Martin Quack, Georg Seyfang, "Femtosecond intramolecular dymanics after near-IR excitation of CH3I, C2H5I, CF3CHFI, and C7H8 molecules in the gas phase and in solution", Proc. SPIE 5337, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications III, (14 June 2004); doi: 10.1117/12.530069; https://doi.org/10.1117/12.530069
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