Abstract

Unimolecular reactions based on the Lindemann - Hinchelwood mechanism are important to understanding combustion and atmospheric processes. The main feature of this mechanism is the energy transfer probability distribution function, P(E',E). We have chosen to study P(E',E) through gas phase collisional dynamics probed with IR transient absorption spectroscopy. Post-collision absorption line widths for the pyrazine-N2O system are used to calculate lab frame translational temperatures. The translational temperatures reveal that collisions with large rotational energy transfer also transfer large amounts of translational energy. For J states >47 the relationship is linear indicating a constant impact parameter. Line widths for J=47 through J=59 also showed that there is no out-scattering from these states, in contrast to work performed previously in the Sevy group. The discrepancy between these measurements prompted a complete analysis of the causes of noise in the experimental system. Defective instruments were identified and noise sources localized, including IR diode frequency jitter. Improved experimental techniques and troubleshooting guides are explained for future researchers in the Sevy group.

Degree

College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry

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