Dynamical study of water catalyzed HF-elimination reaction of CH2FOH.(H2O)n clusters induced by vibrational overtone excitation

PHYS 313

Kaito Takahashi, takahask@colorado.edu, Zeb C. Kramer, Veronica Vaida, vaida@colorado.edu, and Rex T. Skodje. Department of Chemistry and Biochemistry, University of Colorado at Boulder, Campus Box 215, Boulder, CO 80309-215
Vibrational overtone induced unimolecular reactions are fundamentally interesting and are potentially quite important as new pathway for atmospheric photochemistry. Atmospheric organic species tend to accumulate on the surface of aerosol particles and thus water may play an important role in the chemistry of these species. To probe dynamical effects that may be of relevance to the chemistry of Secondary Organic Aerosols, the intramolecular dynamics of hydrated organic molecules is modeled following excitation of OH-stretch overtone state. Using the direct dynamics method with B3LYP/6-31+G(d,p) , we performed a theoretical study of the reaction dynamics using water clusters of increasing size for CH2FOH.(H2O)n+hν → CH2O+HF+nH2O (n=0-3). Water significantly lowers the barrier to reaction through a multiple H-atom transfer mechanism. The key feature emerging from this study is the intricate competition between reaction and energy dissipation into the low frequency modes.

PHYS Poster Session - Water Mediated Interactions
7:30 PM-10:00 PM, Wednesday, August 20, 2008 Pennsylvania Convention Center -- Hall C, Poster

Division of Physical Chemistry

The 236th ACS National Meeting, Philadelphia, PA, August 17-21, 2008