IVR Dynamics of Vibrational Levels of the \nu_1 Mode in (CF_3)_2C=C=O Molecules Excited by Resonant IR Femtosecond Radiation

Journal of Physical Chemistry A. 2019. Vol. 123. No. 4. P. 771–779.

Alexander A. Makarov, Laptev V., Kompanets V., Pigulsky S.

The intramolecular dynamics of vibrational levels (up to v = 5) of the
\nu_1 mode in the (CF_3)_2CCO molecule that is induced by a multiphoton selective
excitation of this mode by resonant femtosecond IR radiation has been studied. The
times of intramolecular vibrational energy redistribution (IVR) from each
vibrational level to remaining molecular modes have been determined. In
accordance with theoretical predictions, a decrease in the IVR time with increasing
quantum number v has been observed for the first time. A sharp decrease in the IVR
time (down to 1.5 ps) at a wavelength of 2129 cm−1, corresponding to the v = 3 → v
= 4 vibrational transition, is revealed. It has been shown that, with a negative chirp of
a femtosecond radiation pulse, the population of high-lying vibrational levels of the
ν1 mode increases significantly.

 

Keywords: polyatomic molecule, intramolecular vibrational redistribution, многоатомная молекула, внутримолекулярное перераспределение колебательной энергии, IR multiple-photon excitation, laser femtosecond radiation, ИК многофотонное возбуждение, лазерное фемтосекундное излучение