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Bimolecular Reactions |
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 Our
lab is interested in understanding the effect of different vibrational
motions on the course and outcome of a condensed phase chemical reaction.
Our work is meant to compliment research in the gas phase that shows how
different vibrational modes can have different effects on reaction dynamics.Time Resolution The timescale of condensed phase interactions is about a billion times faster than that of low density gases. As a result, we use ultrafast laser technology to prepare our reactants and follow the dynamics of the reaction. We pump several non-linear optical setups with 100fs laser pulses in order to prepare the wavelengths required for our experiments.  Spectral Resolution We have recently incorporated UV-visible and IR array detection in our lab. The UV continuum, 350nm-800nm, is created by focusing 800nm light into a sapphire or CaF2 substrate. A Potassium Niobate Optical Parametric Amplifier (KNbO3) generates pulses tunable in the mid-infrared. Both setups allow for the collection of transient spectra at various time delays. Probing Reactants and Products We are currently studying hydrogen abstraction reactions. We use a high-energy UV laser pulse to generate a radical species in solution by photolysis of a precursor (Cl2, ICN). The radical can abstract a hydrogen from a solvent or solute molecule. We can use a time-delayed UV-visible continuum probe pulse to monitor the population of the radical species to observe the dynamics of the reaciton in real-time. By using light from our KNbO3 OPA, we can also monitor the presence of the reaction products. The ability to probe both the disappearance of the reactants and the appearance of the products allow for a more complete picture of the reaction. 
Future DirectionsThe ultimate goal of our lab is to gain a better understanding of the dynamics of a reaction in solution. One direction towards this goal is to study how the solvent affects the product energy distribution of a reaction. Our current reserach on hydrogen abstraction by the CN radical is an ideal system for energy disposal due to the reaction's high exothermicity. Another possibility is to study the effects of vibrational excitation on the course and outcome of the condensed phase chemical reaction. |
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