In this experiment, we measure the rate of vibrational
energy redistribution in molecular systems in dilute solution. For example,
we vibrational excite the acetylenic CH stretch to the first excited state
and measure the time scale of vibrational energy localization in the
acetylenic CH stretch in dilute carbon tetrachloride (CCl4) solution. This
study of intramolecular vibrational energy redistribution (IVR) has been
performed in isolated gas-phase using high-resolution infrared spectroscopy
so far. Knowing the basic mechanisms of energy redistribution, we are
extending the study of IVR into the solution phase, where solvent molecules
can modify the relaxation dynamics of the solute that is being studied. For
the study of vibrational energy relaxation rate in solution, we use infrared
pump-probe spectroscopy, where an intense pump pulse vibrationally excites a
molecular bond and a weak probe pulse monitors the decay of the population.
The current study shows that two mechanisms are involved in the vibrational
energy relaxation process; IVR and solvent-induced IVR.