Reactions of Highly Excited Molecules: From Supercollisions to Super-reactions?

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Amy Mullin of Boston University is supported by a grant from the Experimental Physical Chemistry Program to continue and extend her studies of the effect of internal energy on collisional relaxation and reactivity for highly excited polyatomic molecules. Pulsed uv laser absorption will be used to excite the molecules and transient ir absorption will monitor the internal energy distributions to determine the energy transfer and reactive cross-sections. Specific studies to be conducted are: (1) energy dependence of super elastic collisions (pyrazine by carbon dioxide), (2) the influence of quenching species on collisional relaxation (pyrazine and pyridine by water and carbon dioxide), (3) theoretical modeling of superelastic relaxation using trajectory calculations to determine energy gain by the quenching species (the system in (1) and pyridine, 2-picoline and 2,6-lutidine with water) and (4) influence of excitation on chemical reactivity (benzene with a series of radicals).Activate molecules play an important role in chemistry and biochemistry at many levels in influencing the reactivity. This work will show how specific excitation of molecules by laser radiation can be dissipated, influence the rates of reactions and can appear as excitation in the reaction products. The data will be used to test theories of energy relaxation in molecules.